This evening, just after it turned dark outside, I went out to move my wifes 1996 Blazer behind my new 2006 GMC Dually. I used the Blazer remote to open the door and started the Blazer. I turned on her headlights and positioned the Blazer behind the dually. As soon as the Blazer headlights hit the rear end of the dually, the dually yellow rear lights and fender clearance lights started to flash. A few minutes later another set of headlights hit the rear of the dually, on an angle, and the dually flashed again. Later I tried to reproduce the flashing, but have been unable. Anyone know what I am seeing??? Thanks