Same with my carbotechs, too thick for dampers when new. The inner rubber caliper seal flexes when you apply the brakes and then unflexes and pulls back the piston slightly when released. Brembo has newer seals out now designed to enhance the piston retract. The rotor run out and wheel bearing play push the pad away but the pad is always very close. On the flip side, Some racers run springs behind their pistons to keep the brake pad more firmly pressed against the rotor between braking to prevent pad knockback. I'm not quite there yet
I imagine this dies add some slight additional wear and heat...