On the par-4 fifth hole during the final round of the U.S. Open, Dustin Johnson was about to address his putt when his ball moved. Johnson did not ground his club behind the ball nor did he appear to touch the ball, but he called a rules official over at the time anyway and was told that he was fine and would not be given a penalty and to play the ball where it was.
Everything was fine until Johnson was approached by a rules official on the par-5 12th tee box and told that he may be assessed a penalty for causing the ball to move. This got Rory McIlroy, Jordan Spieth, and Rickie Fowler fired up and they slammed the USGA for telling Johnson about the possible penalty during his round.
USGA rules official Jeff Hall was called into the Fox broadcast booth where he told Joe Buck and company that there appeared to be no other reason for the ball to move except for DJ placing his putter close to the ball during his practice stroke, and that the only reason they chose to tell him was so he would be aware of a possible penalty and could “adjust his strategy accordingly.”
This is one of the main things that makes golf frustrating. The rules aren’t clear and a player who calls in a rules official and is given a ruling during play should be granted that ruling through the end of his round.