He answers this by letting out a breath into her hair and making it flutter around a little. It might not be a clear yes or no, but it was definitely a response at least, so maybe she is Dr. Doolittle, just a bit.

(Though really, it's obviously because she's an adorable and easy-to-fluster red head. Obviously. So, that would point in the direction of "because she's cute and nerdy".)

He's pleased she eased up a little though - he never had any plans of actually hurting her. Maybe messing with her a little, but not hurting her.