Luna doesn't see anyone else at the moment so she doesn't know who else Jeremy could mean right now, but she chooses to believe him when he says it wasn't directed at her. That begs the question of what he did mean by it, though. She comes a little closer, slowly so that he isn't startled, to get a better look and to give herself a moment to check their surroundings again. No, she doesn't see anyone else around - or if someone is there, they're hiding for now.

"Did you see something?" she asks once she's near enough to Jeremy to talk normally. "Or...are you hurt?" She doesn't see any obvious recent injuries and it wouldn't explain the rude gesture, but a painful injury would shorten someone's temper. Certainly people have gotten angry over less.