A polite smile arrives on time. Quick, bright, easy to file away as manners.

Hers starts coming late. He says something a little bold, and for half a second she gives him nothing. No giggle. No raised eyebrows. Then the smile appears, slow enough to look chosen.

It is not big. Big would almost be safer. This one looks like she heard exactly what he meant and decided not to punish him for trying. That tiny delay is what sticks. Later, he can remember the line he said, but mostly he remembers waiting for her face to answer.