He's smiling wider than he should, a return of that stupid open expression he'd work as they left the bathhouse. It's something important, evidence that he's with investing in, and he feels it through his whole body just then.

And then he realizes he must look like a fool, standing there and smiling down at her, and he tries to tame it back. "Of course. Thank you. Er - goodnight."

Better to make his escape now before he spoils things.