Ok, so we have the same issue then. I load up the assistant software and try to perform a calibration and sometimes, the aileron channel will not remain centered at the end of the process. However, if I reboot the unit and try again, I get all greens. I'm beginning to suspect it's a firmware issue with the unit itself, as it's brand new and has never even had a hard landing, let alone a crash.
If I was consistently getting an out of calibration aileron channel, I'd be prepared to accept it might be an installation/location issue, but the fact that most of the time it calibrates perfectly suggests it's the unit itself and not anything I've done.
I think the best idea will be to contact DJI and ask them directly.