Thanks daug - no, no problems with the suspension or frame. I had one H**L of a time getting the rear control arm bolt out (bolt ceased in the bushing which bent the joint abit), but I assume that its back into shape after re-installing the bolt (would bring the joint back into alignment).
Frankly, I think the GM shop just looks for stuff to fix (never seem to find this stuff while the car is on warranty) - I don't trust them as much as the local shop. They said the right rear wheel was out of alignement, but their own spec sheet shows the "misalignement" is within tolerance.
I really hope someone just knocked a wheel weight off!
BTW, something else I did notice last night - I check the front discs and rear drums out for a future brake job. I noticed that the drivers side front disc appeared to be rubbing on the caliper slightly (build up of rust and possible ceased caliper pins). Not sure if this would have an affect.