I dunno, Alton seemed kind of out of it IMO, he looked like he was either annoyed, or not interested, or just angry to be there. I felt like he was disconnected from the whole thing.
Unfortunately, that's just the way he is now. He's trying to play up the 'goofy scientist' schtick, hence his new wardrobe including bowties, as opposed to the old everyday guy vibe he had going on during Good Eats. He was the same way on the Craig Ferguson show as well as a few other appearances recently.
I much preferred the old Alton.