Interesting - looks like a protest was filed but overturned.
"But while Petela missed the podium, his coach Dave Welsh asked for an official protest to disqualify senior standout Grant Fisher of Grand Blanc, Michigan.
The Stanford-bound Fisher ripped a head-turning 4:03.54 to win by more than five seconds but stumbled over the rail on the final turn and stepped onto the infield.
Welsh was told his protest would not be honored because Fisher did not gain an unfair advantage and was not running in a pack when he stepped off the track."
The reasoning they gave sets a dangerous precedent and did not follow the USATF rule posted above. Obviously nobody was going to catch him but how close do others have to be? How many steps inside the track could he have taken? Many questions on when you and you do not DQ someone for running inside the rails.
I wouldn't have protested, but now that I know someone did, they made the wrong call and my guess is they would have felt like jackasses if they had DQed him so decided not to do so. If a runner was alone in fourth place with nobody around him and this happened, my guess is they disqualify him.