I'd do nothing, if faced with a similar circumstance. As some PP's have written, your son was being rude (talking), and the teacher pulled him up on it. Perhaps her wording wasn't ideal, but then again, perhaps his retelling of her wording wasn't 100% accurate either... I think it'd be a pretty difficult conversation to bring up with a teacher- a bit 'he said, she said' about something which is relatively minor. Point was, from the teacher, that your son shouldn't have been talking. Lesson learned.
