Thank you all for the thoughtful and candid replies! I completely understand that this teacher didn't mean anything harmful by it, and in fact probably thought he was giving me a compliment. I also realize he is from a different generation when things like that were still normal. And I wasn't offended so much as I was caught off-guard since my school is generally a very progressive and professional place to work. I think what got to me was: 1) Being called a "girl" which to me will always sound somewhat disrespectful, being a 30-something woman. I don't think most men would appreciate being called "boy." 2) Being uncomfortable and not knowing how to respond, so I ended up saying something that seemed to make it even more awkward, which made me then feel guilty, as if the whole thing was somehow my fault. I realize that I do have a tendency to be hyper-aware and to over-think things, but the more I think about it, the more I think that while I could have responded better (perhaps by saying nothing at all), it was not my fault that someone else put his foot in it and put us all in a potentially awkward conversation. All that being said, I'm sure the whole thing has been forgotten by anyone but myself, so I am going to shake it off. My take-away: next time someone calls me a "girl" in a professional situation, I will just do my best "not impressed" face and refuse to go to that level!