brakes

It sounds like you have a worn out caliper. Have it examined by a quality and reliable mechanic. However,if the back does wear out before the front and there is no caliper problem, then it is nothing to be alarmed about.

The only thing that would make sense to me is that you have a brake caliper pin that is sticking. This might not cause the car to pull because it is the rear wheel. If this is true then your gas mileage should improve if you get it fixed.