There was incidental contact at the bell lap between Mulherin and Leeder. The foul was when Mulherin put his hand between Leeder's shoulder blades and stiff armed Leeder into lane 3, causing Leeder to stumble and lose any momentum he had going into the last lap.
The referee on the inside of the track raised her flag for a foul. This had nothing to do with the FSU coaches yelling, as they were yelling at the referee on the OUTSIDE of the track who claimed he didn't see anything.
Va Tech can whine and protest the call all they want, but it was a blatant foul. The unfortunate part was that the meet was not officiated very well as there were many, many, incidents that should have been flagged as fouls that weren't, and then, when they finally do call a foul it is on the hometown kid.
But, Mulherin took the chance by throwing a blatant foul on another competitor and got burned. Same thing as speeding. Many try to get away with it, and only some get caught. Mulherin was speeding (as many others were this weekend) and was flagged down for the ticket.