We were driving through Schertz TX during the noon hour going east on a main thoroughfare. We both had been watching our speed carefully and abiding by the speed limit signs we had seen. We were pulled over by a motorcycle policeman who claimed we were going 36 mph in a 20 mph school zone. Neither of us had noticed any flashing yellow lights nor any school children present. We were driving a rental car with out-of-state license plates. The officer was pleasant enough. We are suspicious that we had fallen into a speed trap.