There is or was a close up of the club head and ball during the practice swing that clearly shows that his club head hit a twig that was also under the ball. The twig moved and that caused the ball to move. That said, if it was or was not readily apparent is pretty debatable. To be honest, while I understand why they are there, I really don't like this slightest of movement standards for causing a ball to move and wish they would change it something that is more in keeping with a ball that moves significantly and then define what that is such as the lie is improved or moves more than "x" inches in any direction.