I replaced my rear brake pads a few weeks ago, and when I was trying to retract the brake piston, was able to do so by using a clamp and pressing it into the caliper. While it took more force than I was expecting, it did retract fully. I just read where the piston is supposed to be turned while pressing it in. Curious why I was able to press it in without turning. Brakes seem to be working fine, and the parking brake is working as well. Does anyone know if what I did should be possible without damaging the caliper?