I don't see why he would go to the monitor if he didn't award it.
If he did. play stopped at the point of the infringement, not when the ref blew the whistle, so it would have been stopped before the ball went out of play.
I listened on the radio and Warren said he gave it.
If it wasn't given, there was no reason for him to go to the monitor to review it and say it's not a penalty.