I never had any problems until the first time I calibrated the compass. Now I'm having erratic problems in flight. Today I went to a new field and calibrated the compass before I got it off the ground. The calibration went well and I was sure to be in the middle of an open field, away from the TX and the iPhone. No powerlines... Nothing... It flew perfectly for quite some time, then I noticed it wasn't responding correctly to input from the TX. It wasn't hovering properly. I carefully brought it down and when it was closer to the ground it was reacting as though I was giving it forward stick. If I pulled back on it I could slow the speed quite a bit. When I got about two feet off the ground, I cut the engines and it tumbled just a bit. I calibrated the compass again and it seemed to go as smoothly as last time, though I only flew it close to the ground for a limited time. Between this and the battery issues, things are getting a little scary here... Anyone else seeing this?