B.B.
If you can't see anything wrong with that area, it could be anything, try looking at his behavior. My son(3 in a few weeks) scratches and rubs his face when tired/sleeping and always has. I always know when his nails need trimmed, because he really scratches. Suprisingly, a lot of kids do ear stuff(pulling, scratching, sticking hair in the ear) when sleepy. I still stick my hair in my ears when I'm sleepy and have been told that I've done this since the age when my hair first grew long enough to put it in there! Seriously, it feels really good! I have 2 friends with little girls that do the same-see if he's only doing it before napping/sleeping. If not, or it becomes excessive, call the Dr.