It might be just his age, but it also could be an early sign of OCD. When looking back my parents can track behaviors in me from before I can even remember that now occur to them may have been an early sign of my OCD. Of course, they'd never heard of OCD until I told them about it in high school and never knew anything about it until I was diagnosed at 18 so they just thought I was, uh, a little odd? I had the symmetry issue, not only had to always have something in each hand, but if I pointed to something I had to point with both hands. Often if I had an itch on one side of my body I'd have to scratch the other side in the exact same place. I couldn't step on cracks. All kinds of stuff. You never know... and it really wont matter because I doubt even if it is OCD that there is anything anyone could do about it in a kid that young, but just keep an eye on him... see what happens as he gets older! Hopefully its just a "terrible twos" issue!