The first part of my compass calibration (rotating in normal flight attitude) works fine — I get the green LEDs after a little over one rotation. But when I do the second part (rotating nose-down) instead of returning to green, LEDs display slow yellow flashing, no matter how many times I rotate. Return to horizontal mode and re-rotate, and I get green again. The bird seems to fly reliably if I've done that, but the fact that it's not behaving as it should makes me uncomfortable. Anyone else experience this?