I've had something similar happen on my OEM system and DTC70 pads. Somehow the pad got caught on one of the tabs and the caliper, and then flexed the pad causing it to stress the pad material. I'm lazy and didn't catch it initially. When I finally changed the pads, the pad material was not even laminated to the backing plate and the backing plate was warped. Be extra careful with the install.
All in all, it's disappointing that BMW still uses such a crappy design - even if beefed up to handle the duty-cycle for the M3. It works well enough...but it's not an over engineered design.
I run PFC08s on the RS and they seem to hold up to abuse. The RS is about 7 seconds faster around TWS (in my newbie hands) than my M3 and the PFC08s don't even blink an eye.
Britax Carseat | Diaper Kit | Redneck Cutouts | Turner Studs | Bassified Individual Audio