Not that. All sorts of animals do all sorts things without having even ever before met or communicated, much less kissed each other on the face. Including people. It's not unheard of, why would that matter anyway. Even aside from not mattering who kissed what where first or second, or earlier or later, or at all. That talk about what it looked like while Kimiko was turning around and getting situated was trolling, same as when Erika was looking up at Largo during the machine testing escapade. Up to something, not looking much like what it supposedly was and probably wasn't, and then at least somewhat if not fully conclusively established by events as not being that at all.
Of course nothing requires any convoluted reasoning, especially if it's clear what was going on and why. But we already have some 1400 examples of how things usually work to fall back upon for future expectations. Which are that not everything goes where it appears, and much doesn't ever get explained. Guessing at things in the middle is convoluted sadly, because of precedent establishing that as the natural order of things. Which even after they're over they're often not much clearer.
But we don't need it that difficult. Forget acting as if you've been ended, portraying an Analogue that must die for the sake of society and stability and the good of Megatokyo. Nevermind that the Kimiko that Erika was talking about has changed in lots of extensive ways. Had specifically been patient and understanding and empathetic to everyone including and especially Piro. It doesn't matter if Kimiko did any of moved back into old ways pre-fame and pre-Piro, snapped, went animalistic, is channeling Miho, has become Miho, is doing what she is doing is only because of story. We still can only guess (although certainly given 1482, many things are considerably clearer even though still ongoing and not yet fully resolved).
Imagine you are in a situation where you just figured out you are substituting for a metaphysical magical powerful something that is just as out of the natural order of things as had been suggested that you'd been ignoring. You emotionally drain yourself portraying the demise of somebody you're trying to help, burying yourself in the mindset and manner of that and then of being dead. Stopping to tell the other person you love them, in character, but probably for yourself rather than to give realism. The other person trying to save her then carries your body through gaps and wreckage and mystical pathways. One imagines they didn't know about all the monitoring or the Ninja running interference, but he was aware they were being tracked still, things weren't over, they were being chased somehow. And you all the while lay there not answering or talking, and as far as we know, not even really listening; being somewhat dead, putting yourself in a coma, immersing yourself in a hypnotic state. Then you get to safety, but it's not, it's a car under fire being chased etc. You stay in character (of some sort). You're carried into a vehicle, covered with broken glass, that the other person lays upon. Would you be scared, anxious, worried about your mission, wanting to stay in hiding and in character of dead untalking unmoving which is the entire reason for all this. Seems more likely and more normal than wanting to show the other person how much you appreciate and love them by being physical and potentially even ruining everything you just did. Doesn't seem wise, thoughtful, intelligent, or likely in the circumstances. It seems more akin to deciding you don't care about the money or getting away when you're in the middle of a bank robbery. Piro himself reaction-wise is apparently quite very much thinking this is odd and weird and out of place.
No matter how long it's been. Let me see. It's been a couple of months since we met Kimiko if we start in 0. Starting at things happening in 1, including the break, that's been about three weeks. 9 days to Ikebukuro, where most of the relationships were established more or less, 10 days Miho is "missing" things solidify, and 3 days since where it's all gone crazy. Although that's clouded by how long it seems out here, story-wise and other-wise. Certainly a lot has gone on in MT, and maybe it's like cat years. Their three weeks is three months or years, whatever. Erika and Largo are where they are and it appears quite normal usual expected, and really given their personalities as we've seen them over the last 3 weeks, the pace for Kimiko and Piro is probably just as normal usual expected for them.
So. We're to believe she, herself, of her own will and reasoning, suddenly, with any sort of thoughtful rationality at all, gets some urges and decides to act upon them, in a car escaping the police etc after acting to be quite dead for a number of tense minutes. Of course it's possible, maybe it's even likely. Perhaps Kimiko is following and carrying out an "Idol strike" upon Piro in much the same way Erika did to Largo, just at a far more fanciful and exotic and tense busy scary unprivate time in the story. Maybe Kimiko knew the situation was over, that Piro would be open to her making a move because it was right and what they had done to bond there wasn't easy. That he deserved a reward for caring about Miho and those like her, and for helping Kimiko do what she'd decided to without him having much much instruction. That now was the time, Megumi can't see anything or she doesn't care if she does. That Piro wouldn't consider it manipulation or too public or too forward too fast too soon. All that could fit. Yes, those who feel a vibe that it's out of place for her to do now and this way could be quite wrong, because they don't know her mood or what she's thinking any more than those who think this is a fine expected fitting realistic reaction and action by her. One, the other, both, neither.
Of course all she's done is kiss him a few times. And while we know more as of 1482, we still don't know yet what he has done or not. Going by the car fade out down the road, standard trope stuff says things are happening we can't be allowed to see, and it might be just like that. Yet it doesn't have to be. So even if we go beyond 1481, we still don't know if her behavior is strange. Strange being like if Piro doesn't go along or does and later regrets it, or if Kimiko does or says something later that shows not all is normal. As of now in 1481 or even at the end of 1482 with the additional information it has, there are not facts. There are assumptions based upon innuendo, ideas influenced by trope, notions based upon perception, expectations derived from opinion, thoughts clouded by desired outcomes.