When I was little, because my hair was fine and flyaway (and because she was a not very good frustrated hairdresser), sometimes my Mum used to cut it much too short.
The gentleman who lived next door to my grandparents was Chilean. His idea of being friendly and playful was to tease me about my hair and call me "little boy". I used to feel quite embarrassed and uncomfortable about this. As I grew older and got used to this man, I realised that he was nice and it was just friendly teasing. In retrospect I wonder if it was possibly a cultural thing - not necessarily cultural in the sense of nationality but in the way that different families interact differently.
Is this lady making these comments in a jokey way or in a serious, obviously vindictive way? In either case, I would be inclined to speak to her calmly on her own and tell her that her remarks may not be meant unkindly but they were causing distress to my son. If the behaviour continued, I think that would suggest nastiness. In any event, if the remarks continued to be made, I would definitely make a point of avoiding her.