Originally Posted by Lil_Deuce_tCoupe

Common issue on the tC - it's not the piston sticking, it's binding of the caliper on the slider pins. As discussed previously in this thread, they need to be lubed - otherwise, the calipers do not 'release' when no pedal pressure is applied. The pads stay in contact with the rotor.
Seems to be especially bad on the rear, at least it is on mine. There are two pins on the fronts, but only one pin on the rears. On mine, the rear pin was completely frozen in the caliper. Fixed it once, found it happened again later, really bad on both rears, and slight sticking on both fronts. So I lube all of the pins now, front and rear, every time I rotate the tires - every 10K miles. I do have 184,000 miles on the car though....
Another sign that the pins are sticking, pedal will not be firm, even after bleeding. That's how I found mine were sticking, pedal went almost to the floor.
Easy to tell if they are 'free' or stuck - on the rear, remove the caliper retaining bolt, and the caliper should easily pivot upwards on the pin. Once up and away from the rotor, you should be able to easily slide the caliper in and out on the pin. If the caliper won't pivot up, or is very difficult to move, good chance the pin is sticking / binding in the caliper bore.
Same on the front - if you remove both of the pads (or just one), this will give plenty of space for you to be able to slide the caliper in and out on the pins by hand. Should slide easily. It it doesn't move, or is difficult to move, the pins are sticking.