Rxcalibur

Installed a stock replacement power antenna today. The antenna unit was indentical to the unit it was replacing. When I was finished I started the car up and the only thing that happed was the antenna mast retracted about a 1/4" back into the power antenna unit. That's the only noticable diffenrence in movement that I have seen with the mast. The mast appeared to be completely retracted before I turned on the car, the tip of the mast was flush with the rubber seal around it. The radio was set to on when I turned the Rx7s power on. So I have no idea what the problem is. Has anyone had the same problem happen or seen this happen before?