ASHBURN, Va. -- The NFL said Monday that a 30-yard touchdown run by Carolina Panthers running back DeAngelo Williams against the Washington Redskins should not have counted because of an inadvertent whistle.

The league said that the Panthers should have instead been offered the ball at the 17-yard line -- at the point where line judge Thomas Symonette blew his whistle because he mistakenly thought Williams had stepped out of bounds. Under the rules, Carolina could have also chosen to replay the down at the 30.