Rough and tumble play alone is not an indication of anything other than being 2! Just if there are lots of unusual or extreme sensory-based behaviours there, there can be cause for concern... but if nothing but this is out of the ordinary, I doubt it's your issue. You can always google SPD to see if it rings any bells, but sounds unlikely.

I agree with the others about ruling out doing it because of discomfort.

If she is doing it for pleasure, it's a self-reinforcing behaviour - instant feel-good, therefore do it more. Like Keta suggested, if this is the case, keeping her occupied and feeling good through other activities might help to break the pattern of behaviour.