Q: Caliper piston failure after accident on it's corner

This is more of a question of how something could happen. I have a Jeep and it was struck on the left rear, It was hit on the body, the wheel was destroyed and the rear end was bent. My question is, the brake caliper on that side, which has that plastic, bake-o-lite type material for a piston, was reused since it has no signs of direct signs of being struck or visible damage. Could the piston inside the caliper have taken enough shock from the hit to that side but still functioned for awhile and could it eventually stick, or break apart inside? I was told that with it's posricion and make up, it is possible the piston could have fractures that are not visible. It is making a noise on that side but the body shop that repaired the car claims there is no problem they can see. I have a problem with so much damage that was caused in that corner of the car and the fact the caliper is touching the part that obviously had a tremendous shock

My car has 140000 miles.
My car has an automatic transmission.