P.P.
I honestly would appreciate that the teacher is being honest. I think she is trying to solve the issue so your son can be more comfortable, obviously is in everyone's interest that your son is happy at school.
I had a teacher once tell me that my daughter was climbing on the furniture and that she got in time out for it because it was dangerous. she told me to reinforce the discipline at home and to please watch if she climbed at home too.
I talked to my daughter (she was 3.5 at the time) and explained to her how dangerous was to climb on chairs etc.
She never climbed on furniture again at school or at home, and I was grateful that her teacher was concerned for her safety.
If your son's teacher's didn't use a bad tone or sarcasm to address the problem then I wouldn't take her comment badly.
I hope this helps! Good luck!