[RyanCahoon]

Could be drift, but it could also be calibration error. In either case, if the rig is left still, it could be observed to slowly drift offcenter of its own accord. If it moves relatively fast and always in one direction, it's a calibration problem. If it's slower and seems to be jittering back and forth, it's more likely to be drift.

Either way, as [Chris Hibner] said, more details are necessary. Posting your code may help as well.

--Ryan