Referee Madley did not see the incident during the game which was caught on television cameras. The footage appeared to show Gallagher's elbow connecting with Joe Allen's face.
As the referee did not see the incident during play the footage can then be referred afterwards with respect to potential disciplinary action if merited. In this case a three game ban has been handed to Gallagher starting immediately meaning he will miss the Norwich game.
Preston have decided not to appeal the decision.