OAKMONT, Pa. – Dustin Johnson had another run-in with the Rules of Golf during the final round of a major championship, but this one didn’t keep him from hoisting the trophy.

It started at the fifth hole, when Johnson’s ball moved on the putting green. He took several practice swings next to his ball while preparing for his 4-foot par putt. The ball rolled backward slightly as he went to address his putt. Johnson consulted with a rules official and was not penalized at the time. The USGA continued to review video of the incident, though, and he was told on the 12th tee that a stroke could be added to his score after the round.

The contenders had to play the closing holes uncertain of their standing.

Johnson was penalized after the round, but all that did was reduce his winning margin to three shots. He maintained his innocence in his post-tournament press conference, but also was indifferent because he still held the trophy.

“I still didn’t want the penalty. I didn’t think that I did anything to cause the ball to move, but at the end of the day, it didn’t affect what happened so it doesn’t bother me at all,” Johnson said.

He was penalized under Rule 18-2 (Ball Moving after Address). A one-stroke penalty is applied if a player’s actions are deemed to be the likely cause of his ball’s movement.

“After looking at video, the actions he took could have caused the ball to move,” said Jeff Hall, the USGA’s senior director of rules and open championships. “We asked if there was some other reason the ball could have moved. He didn’t state a reason.”

The final decision was made after the round because “we had an opportunity and an obligation to explain the rule, and doing that in the middle of the 12th tee just didn’t seem like an appropriate time,” Hall said.

Johnson held a two-shot lead when he was told that he might be penalized. The other players remaining on the course were informed about the situation before Johnson finished the 12th hole, USGA officials said.

The possible penalty round loomed over the tournament’s closing holes, causing confusion among fans and media. Shane Lowry and Scott Piercy, who both finished second, said they weren’t affected by the incident, though.

“They told us they were talking about it but we didn’t ask any questions,” Piercy said. “We were involved in what we were doing. We didn’t even ask what (the incident) was.”

This is not the first time Johnson has been involved in a controversial ruling late in a major championship. He held a one-shot lead when he arrived at the final hole of the 2010 PGA Championship at Whistling Straits. He hit his tee shot into a bunker well right of the fairway. Fans crowded around his ball, making it difficult to distinguish the hazard from the sandy soil around it. Not realizing he was in a bunker, Johnson grounded his club before hitting his second shot. He made bogey on the final hole to tie Bubba Watson and eventual champion Martin Kaymer. Johnson was informed shortly after holing out that he had incurred a two-stroke penalty.

Johnson admitted that he thought momentarily about that incident after being informed that he may be penalized.

“Just one more thing to add to the list, right?” he said. “At that point, I just said there’s nothing I can do about it, so let’s just focus on this shot and go from here. I just kept telling myself it’s just me and the golf course.

“At the end of the day, it’s just ultimately up to the USGA to make the final decision,” Johnson said. “Fortunately, it didn’t affect the outcome.”