The expressions working their way across Crowley's face suggest that it's not so much the case that he doesn't know what to say, as that he doesn't know where to start.

(Something that might be a clue, though: they're all variations on 'amusement'.)

"Have we... not spent decades and decades not seeing each other once? Not even on the same landmass, even?"

Well, barely. The Isthmus of Corinth is a pretty shoddy excuse for a bridge.