Check your bolts. If the anti seize is cruddy or not there at all then get some C5-A anti-seize, brush on works best, and start pulling bolts, cleaning and re-applying the anti-seize.
How are you tightening bolts, with a decent click type torque wrench? Double check the recommended torque value from Stretch Devices for your frame type and tension level. There's kind of a range there.
Also, take a roller frame, loosen bolts, put it on your expo glass, tighten up (gently on the glass) and then bring that frame over to your roller master. Adjust the back pad until that flat to glass frame is perfectly flat on the roller master. Sometimes the two are just off from each other.