D.A.
J.,
even the dentist will tell you that this is so normal. They won't even give them night guards at this age. I go to a childrens specialist for my sons teeth and he says its very normal. Most times they out grow it. My son does not do it as much as he did when he was your sons age. I think the dentist worry more if the grinding happens when the children have adult teeth. I wouldn't worry too much.