head shape concern

Rebecca

At what age should I be real concerned about the shape of a baby's head? My baby is now 2 months old and he favors one side of his head when sleeping so that side is flatter. I tried to get him to lay on the other side and I try to hold him in my other arm to make him stretch his neck that way. I have talked to my doctor and he said the head continues to grow for awhile so i shouldn't worry but I think it is getting more noticeable.