It may have to do with where you are. I've had that happen and then be fine after a reboot. Some time ago it seemed to be stuck on East no matter what position. Even went to a Verizon store and added the same GPS app to a Droid demo to see if it was different. The tech said I had too many apps running at the same time (they must've looked at my app drawer as I had turned it off prior to giving it to them).
They ended up doing a factory reset, which fixed it. It still does it from time to time, but I think some of that is because I'm in a car or trolley.