"Mm." Is her only agreeing sound, at first. She isn't sure if this is a good enough time to bring it up, when things are still so tentative, but... now that Jeanne's not facing him directly, she finds it easier.
"Of course I would. Like you said, it's very important for girls, and that includes their date for the evening." Subtle? Probably not, but she doesn't react further, even if she does tense up a little.