22450 requires that you stop AT the limit line, not before and not after it. I suspect that f you stopped at the intersection, you probably rolled past the limit line, saw the officer or reached the intersection and THEN you stopped. That's what the officer likely saw. If so, then you are guilty of the offense.
22450. (a) The driver of any vehicle approaching a stop sign at the entrance to, or within, an intersection shall stop at a limit line, if marked, otherwise before entering the crosswalk on the near side of the intersection.
If there is no limit line or crosswalk, the driver shall stop at the entrance to the intersecting roadway .
If you are otherwise eligible, you can take traffic school to remove the point for the violation if you so choose.