He keeps her shirt on (Porthos' shirt, actually), because he does so like the picture it makes. He breathes with some difficulty as he blushes now just to think about it, having seen it in practice so little. "No," he manages to get out steadily, though it's a task, "I didn't know that. Thank you for pointing that out," he says, gulping somewhat as he rolls onto his back and brings her on top of him.