Panels 1 and 2: Free night at the dental clinic. Cool. That building is kind of forbidding-looking, though. And is that a huge hallway or a waiting room? The whole thing looks kind of uncomfortable, but hey, it's free.
Panel 3: What was she impressed by, though? This isn't snark; I'm honestly wondering. He hasn't even done anything yet. As far as we know, their library encounter was the only time they've met before now, and they didn't say anything.
Panel 4: Hey, did you know that people can't really talk when they're in the exam chair and the dentist is working in their mouth? That's a joke that's never been done before, by anyone. (But John almost looks cute here, I think.)