Radio Calibrationen - How often?

Hi,
I have setup my plane with a proper setup of arduplane and did already some flights with quite good results.
The flights were stable and ardupilot behaved more or less as expected.

At the weekend I wanted to start another flight and in MANUAL mode everything was setup fine.
In the moment I switched into any other mode (e.g. STABALIZE) the left aileron setting was completely out of norm level. First I thought the plane is not strait on the ground but this was not the reason.

The only explanation I have is that I have to re-calibrate ether the radio or the gyro - or both.
Does this happened to you as well?

Thanks
Christopher