In a daycare, is it customary (protocol) for teachers to ask the child if they have bruises in front of their parents without any apparent signs?

My son is 5. His teacher asked him that this morning right in front of me and she said that they do that. I not only volunteer up there at my son's daycare, but have dropped him off and picked him up (between me and his mom) 1000 times at least and that has never been something I've heard the teachers ask, especially not in front of the parents.

I talked to the principle and she said that there would be some kind of sensitivity training for the teachers in regards to why they would do that, but the principle also said that the questions are something they should do more often or consistently. What do you think?