J
I really don't know what to give as a proper answer for this, but I would be suspicious on the fact that he took a long time to answer when you asked if anyone was doing that to him. Yes, four year olds are supposed to be innocent from many things, but even at a younger age if something's wrong then they can pick up on that and what ever they're told or have done to them they will think that it's okay and go by it. I would get suspicious about the whole thing and suggest greater things to be done about it.