Yes, with the rear rotor off you can see what is going on with the star screw assembly. I didn't use new bolts when I removed my calipers - maybe I did a bad thing, but it has worked alright for 5k mi. No, 1/4" out of true isn't normal, and would cause some major problems when braking AND driving. Is the small retaining screw screwed into each rotor? On my car, the rotor stayed mostly true until I disturbed it by removing the retaining screw to put on a new rotor - the new one wasn't true until I tightened the lug nuts (just putting in the single retaining screw won't attach the rotor to the hub in a true manner).