Before we condemn your rotors I think what I would do is check the lug nuts. If your guy did not us a tq wrench that is the problem. If your rotors were not warped before the new pads where installed then I bet he used an impact gun to tq the lug nuts down. Have the lugs loosened and tightened back down to the correct specs (funded in your owners manual) and see if that doesn't fix the problem.
Every time I would take my car in for an oil change and free tire rotation the brake pedal would pulsate. I would have to retorque the lug nuts and low and behold the pulsation would be gone! BTW they now use a tq wrench on my lug nuts! :B
Don