Brake pads and rotors are not replaced at mileage intervals, but on an as-needed basis. My son recently replaced his OEM brake pads at 50K miles and I replaced the OEM pads on a 10 year old car at 120K miles. We drive the same roads, but have different driving styles. I coast and use the brakes only when necessary.
I suspect your dealer meant rotors and not wheel cylinders. Rotors can usually be "turned" at least once before they need to be replaced.