Based on how the overall interaction went in the first three pages, I assumed she was just trolling him.
My logic was that the guy wasn't aware of when her cooking class actually started, only that she was meant to have one on the day. Which I think makes sense, since he realistically doesn't need to know when any other classes start, only his own art classes.
She’s really pushing it with the teasing. Now that they’re dating he really doesn’t have to hold back as much as before. This poor girl’s “cookie” is going to get devoured