[RacingRicki]

Go to the following web site that has it recorded. At 4 minutes into the video, hit pause then use your right arrow key on the keyboard to move frame by frame. It actually looks like both cars moved simultaneously but Kurt's red light was on and the pre-stage and stage beams were out before the car moved.

Also, just because nothing on the car is lower than 3" doesn't mean the guard beam can't be activated due to misalignment of the beam or some other reason.