I can't see anything wrong in that pic, but a good way to tell if it's supposed to be there is to compare it to the other side of his head. Chances of him having the exact same injury on both sides are slim - so if the other side looks the same, it's probably nothing.

On the other hand, if there's something visibly wrong and you don't think it's likely to fix itself correctly without help, then it's the vet for you and your little buddy