Thats a new possibility to add to the list, to be honest. Of all the different/weird theories Ive heard, thats a new one. I was wondering if some of the parts were less than superior (they are aftermarket, can't remember what brand). The only thing I've noticed is some play in the torsion arms bushings, not sure how much play is allowed, I know they are made to flex side to side too, so there should be some.
Brake theory would be something that would "hide" I suppose, no real symptoms except for maybe wear being different.

But my question there is why would it cause the shaking of the wheel? Brake grabs, abs kicks in, and since one side is grabbing more, hence the shaking??