Kisame wasn't exactly expecting one to happen, but one could never be too prepared for treachery. It happened far too often, especially in Kiri.

"We do have a particular look; that's true! And what history do you know of my clan?"

Kisame was used to fielding questions about his clan from those outside Kiri, and even some inside, though they should know better, and found that the best defense was deflection. If the man was recounting what he knew, he wouldn't be asking things of Kisame. And it never hurt to know the current rumors about the clan!