[ John is not expecting to see Dave. And yet there Dave is! He gapes for a moment, totally not even trying to figure out what's going on with the pointing, and-- holds back from his initial urge, which is to hug, because Dave is a coolkid. John can be cool, too.

He is a bit thrown off by how Dave doesn't try to speak, though. There's just pointing and then pulling out a PDA. John's forgotten some things, probably some important things, maybe Dave forgot how to talk? Or... Dave was the Time Guy. Maybe he's from John's future and knows John can't hear?

He'll just... stand here awkwardly for a moment and wait for Dave to finish typing... ]