you can be sure a mechanic has looked to that occurance. I've had it several times in my carreer, most of the time it was a misrigging as said, but we also got a spoiler that didn't retract 100% on 1 side, and we even got an old aircraft with a slightly twisted fuselage (hard landing?). That a/c flew many years with aileron trim just within limits. I don't know if that would be tolerated nowadays...
now a question, with the deflection you mention, would a 767 pilot be able to see it if the autopilot gives a continuous aileron input of that kind? As I recall the only clue the pilot has is a sticker on the steering wheel with trim units on it.