1.7 Balls Settling
A ball may settle slightly after it appears to have stopped, possibly due to slight imperfections in the ball or the table. Unless this causes a ball to fall into a pocket, it is considered a normal hazard of play, and the ball will not be moved back. If a ball falls into a pocket as the result of such settling, it is restored as closely as possible to its original position. If a settling ball falls into a pocket during or just prior to a shot, and this has an effect on the shot, the referee will restore the position and the shot will be replayed. The shooter is not penalized for shooting while a ball is settling. See also 8.3 Ball Pocketed.