That's a tough one. He's probably learned this from the boys in school, not neccessarily from being picked on. It was probably best that he didn't cry right then, as he would have been humiliated by that other boy. I don't think you are being over protective. Maybe you could talk to him about expressing his feelings in a safe place, such as at home with you. In fact, it might be better coming from his dad, as he will relate more to a man. Boys are tricky, aren't they? I wish I could be more help. Try to get Daddy to talk to him "man to man".