Do you have anything metal placed close to the Compass. I put my Zaon MRX up on top of the instrument panel and it was at the time a little too close to the compass and was knocking it off by about 20 degrees. Other than I can only guess one of the two screws that calibrate it have moved and your compass needs recalibrating. I would agree its a bit stange but I often find the wet compass is never as precise as a GPS reading.