I'm not sure if I have AS or not, but this is something I've done since I was a small child, and no one could understand why, so I'm wondering about it. I doodled on everything, even furniture and sometimes the wallpaper (my parents made me refarnish my desk once or twice, I remember). It wasn't artistic, or interesting, or anything like that, and I would usually do it without even realizing it, and the doodles were all pretty much identical after a while. It just always seemed to me that there was some hyperactive part of my mind that had to be entertained 24/7, or I couldn't pay attention to anything, and moving my hands the same way over and over would occupy that part for the time being and I could listen to someone and digest what they were saying to me. I would do this during class, or when talking to my parents and everyone always assumed it meant I was ignoring them, but I don't think I'd have been able to do as well without it.
Nowadays I don't doodle as much, but I've found a variety of mindless, repetitive things to do on the computer like resorting large amounts of random data by hand, and the like, and it's become something I do when I feel upset or just need to wind down a bit. Is this an AS thing? Do other people do this?