Things I would check first:

1. Make sure your ailerons are aligned with the wing chord on each wing (Level to the wing) and your wing isn't warped.
2. Aileron servo isn't reversed
3. Make sure your elevator is level. This is especially important if you have a plane with two elevator halves with two elevator servos.
If they aren't aligned they can induce a roll especially if you are pulling back.
4. Air speed. You should only have to bump the stick back to get it to leave the ground. If it is a tail dragger, wait for the tail to come off the ground and gently pull back.