Regardless of the age of the calipers if there was any defect in the remanufacture of the piston or some water in the system the corrosion can form and bind the piston. There is no spring return.

I know a B body caliper can be had for $20, so it can be an easy fix. Does the car pull when braking or normal driving? If not, than maybe both are equal which can push you back to a MC piston not fully returning and preventing fluid return, or a meter valve(hold off valve) if you are using one with debris. G