I, too, found the so-called chirpiness to look like pretty bad acting, but they're definitely preparing an unimaginable contrast for the coming episode(s).
I much prefer this Peter.
Of course, grumpy Peter was cute, but happy/chirpy Peter is fantastic. And I'm sure their main purpose for making him so happy right now is because of what might happen down the road.
I think that Peter has grow and is a lot more comfortable with where he is now, which may contribute to the chipper attitude.
What's That Noise?
I dont mind it too much, but at some points it's really awkward. I'm so use to him being sarcastic or serious. I guess it just really bothers me when he's around Olivia, because (I think) when he's around her he does change, but now it seems a little over the top. Maybe because of the way she's acting around him. But I do like how he's acting with Walter, more like a son.
I guess the only way I can describe the way he's acting is "Ignorence is Bliss"
i think he is just trying to hold the family unit together because as he sees it, they are crumbling for no apparent reason or maybe because of him. So he's overcompensating by being very happy and cheerful. I don't think it's bad acting at all. Believe me, I hated Joshua Jackson's character in Dawson's creek, but I love him in Fringe and have come to think of him as a great actor.
One side of me wants to believe though that on some level Peter knows something big is about to be revealed to him, I mean Olivia and Walter suddenly started avoiding him after Jacksonville and clamming up and having secret conversations, you don't think a person starts noticing things like that and wondering why?
I think he is trying to coax whatever it is out of them, he doesn't want to push them away with his own anger and he's asked them both about it, so he's not totally oblivious. That's also my take on Peter's forced line in White Tulip about him not fulfilling his destiny, he's trying to get a rise out of them, something/anything at this point.