*very startled to see Professor McGonagall there in place of the kitty*

Oh! Errr, hullo there, Professor. *isn't about to suggest she doesn't belong, even though it's obvious she doesn't.

Um, no, you're not intruding at all. *it's a free pub, after all* It is our JAILBAIT teaparty, but I'm sure no one will mind your being here, too. One of the new Professors is also here. *wasn't sure if this was a good thing to say, or not*