This is someone Noah doesn't recognize, and he smiles sheepishly because he can tell he totally just intruded on a private event. He really does have to start learning to use doors.

"Hi," he says, rubbing his cheek a moment and then, realizing he's doing it, drops his hand. "I made cupcakes and I was going to invite her over for one, but I didn't realize she was at..." He glances around, and gives a guess. "Someone's birthday party?"