While flying my MVP on a waypoint mission, it came close to but did not touch electric power transmission lines. I got a warning that the compos needed calibration. So I aborted the mission and brought the MVP home. the error message went away but the MVP did not land very close to it's original home position. Today I did a new compos calibration and executed a different waypoint mission (that did not come close to any power lines). The MVP landed within a few inches of its takeoff position.