*is slightly puzzled by Snape's charades (they're in a bookshop, not a library, after all) and then wonders if the other man has lost his voice*
*politely, but plainly* This is a little embarrassing [it isn't] since I recall that we've been introduced [they haven't] but I wasn't expecting to see you here [that much, at least, is true] and I've forgotten your name.