He didn't say it, but he was suddenly glad they were both the same gender.

At the question, he swept a hand through his hair and sighed, shaking his head.

"I'm not sure. Maybe some kind of... stealth spell, or a glyph or something. I know I didn't do anything, and I've known you for 30 seconds but I'm pretty sure you didn't either."

There's been gossip of this sort of thing going around the school, so his assumptions are going to land squarely on that.