With a couple of exceptions most all the cable operated disk brakes only move one pad. For there to be no rubbing when not using the brake the other pad, often called the fixed pad, needs some gap between it and the rotor. So when the moving pad clamps against the rotor the rotor is pushed a tad and against the fixed pad.

Troul's comments are, in a perfect world, correct for a caliper where both pads are moved in during the braking action. But even with a dual moving pad caliper there is often a slight off center pad movement and a slight rotor pushing. Andy