I believe this is usually called "visual exploration" and is, I think, seen in younger kids as a developmental stage. They may pick up their hand and gaze at their fingers from every angle as if they'd never seen then before.
Have heard about kids with autsim looking at things out of the corners of their eyes, but I think that's because direct focus can be too intense - like you or me looking into the sun or that air puffer they use at the eye doctor's.
Don't know about his doing this as a stim, just know about the "visual exploration" thing from Cole's OT from infancy. Maybe at least you have a name for it now? Sorry.
My baby who will be 2 on Tuesday is really starting to do this alot. He lays down and plays with trains and cars. he doesn't apprear to be looking at the wheels all the time but rolling them around the room and looking at them from all angles. I've noticed this for about a month and it is getting to the point that he is not playing as much with his other toys. We took his Thomas trains and only give them to him a few times a day for a little while. How long is appropriate to let him stim like this. I've heard 20 mins and them distract him. My 4 year old doesn't really have any stims but did flip book pages at this age (I didn't know about autism then). My son at 2 did the same thing and it is considered a stim. What I did was to