The school's psych had asked him if he believed what he had heard from the teacher, that the jews hate the muslims and vice versa and DS replied that no he didn't it. No he didn't because mummy explained to him that there are the good and bad in all races and religions and not to stereotype.

My DH tells me to get over it and that i was taking it overboard
I don't think you're taking it overboard by following it up - because if the teacher has those beliefs and was trying to impart them - then you are looking out for the welfare of his other classmates whose parents may not have imparted the values you have and could be influenced into cultivating a prejudice themselves based on what this teacher said. And if it was a case of the teacher just misguidedly and inappropriately trying to explain existing prejudices as part of say teaching tolerance of other religions etc - than at least the school will council the teacher on being more careful in what he says realizing he is talking to little kids so it doesn't happen again.