I've had my 2007 Prius for about 6 weeks. Several times (probably about 10) while stopped at a traffic light, the gas engine will start cycling on and off every 1 to 2 seconds (The engine will run for about 1.5 seconds, then shut off for about 1.5 seconds and so on). This will continue until the end of the traffic light and the gas pedal is pressed. I took it to the dealer and they said the car checked normal. This does not seem normal, and if it is, it seems like poor design. Does anyone know if this is normal?