I've recently noticed a slight movement of the rear end when at high speeds 70-80mph anytime I accelerate more as if I was going to pass someone. The rear end moves to the right. It can be felt and now after messing with the sensation I can see the movement in the rear view while looking out the back window. I've kicked a few things under there but didn't notice anything. Any ideas? I may have the dealership drive it with me next time I go in for maintenance. However I hate this local dealership. It may be a while.