Peter breaks into a grin upon seeing Dawn. The nerves aren't gone by any means, but they've been replaced with excitement at seeing her. She looks good, but then Dawn always looks good, so he's not surprised.
"Wow. Hey...yeah. Uhm...you look really--really nice." He winces at his word choice. "I mean good. You look really good. Great. Not that you don't always--hey."
Sometimes sticking with the classic greeting is the best thing.