a centimeter is damn near half an inch that would be significant for sure and cause a lot of trouble. You might be meaning a few millimeters. Usually this happens for two reasons, 1) the shaped leading edge of the aileron is larger than the trailing edge of the wing or 2) the hinge line is slightly off center and therefore the aileron sits higher above the wing than is should.

In either case the raised aileron will cause airflow dissruption over the surface and might in fact cause the plane to "roll" in the direction of the raised aileron, as if you were intentionally doing it. It would be acting as though the aileron has been deflected. You could remove the aileron and re drill the hinge holes and correct it if you felt so inclined or you could add sheeting over the surface of the wing to build it up then sand it smooth and blend it in to match the surface, the down side to this is one wing becomes heavier than the other which would mean greater attention to balancing.