Would you call this "making moves on her"?

it was at least a verbal move. SHe perceived it as such and it's her perception that counts. Your random question made her uncomfortable, and I think you should have known it would. Next random question should be "How about them Cubs" or "Do these jeans make my butt look fat" or something a little less high-voltage than "What if I kiss you." Bet GF was concerned when she heard about it.