My son rubs at his fingers almost constantly. I have a theory- he has a huge bandwidth for information, almost like he was made to absorb and to think things through. Hence the sharp hearing, heightened awareness. When there is idle time, his brain fills it in with sensory seeking activities. Not extreme or dangerous, but just a sign of idle capacity somewhere inside.
My DS6 does the same thing...now has callouses on his fingers. It's crazy, but I have to agree that I have the same sort of theory. That's why whenever DS6 has a sensory seeking behavior that lessens or goes away, something new always seems to surface.
