"My present, you mean," is teasing. Now that she has surrendered the lead to him and may openly criticize his execution of the steps without endangering her own competence, there's little reason not to poke fun at him. That's what he'd called it then, wasn't it? A gift.

(Really, there is nothing to criticize—she is hardly so excellent a dancer, and he's deft enough at picking up all the necessary pieces.)

"Oh course I remember it. I have an excellent memory for my property, Mister Ellis."