That's interesting (not too sound too cynical, mind you). When we speak of "visualizing", it's this sort of thing we mean - that we perform "internally" alongside the instrument we're playing. Do you vocalize when playing? Lots of musicians do that (even to the point of being audible in studio recordings). I experience it on instruments myself, but I've never had a stutter in it. However, other movements can be "synchronized" to a stutter, so it seems likely the balance could tip the other way as well. Are there other actions you can think of where you stutter in performing them?