My rear brakes are still squealing after replacing some badly worn pads. It looks to be like maybe there may be a problem with the piston itself because the problem is isolated to the rear drivers side. I'm positive this is the only trouble spot because there are some slight grooves that have formed and the outer pad does not appear to sit right on the caliper after driving it around for a while. When I pulled the old pads, the top part of the pad was much more worn than the bottom part of the pad indicating that the pad is not seating in there properly, which is what I think is going on once again.

So the question is, what could be causing this?