Firstly, the most related AR (9-2-1-IV) directs us to administer as a dead-ball foul when it is not clear when the diving action began - which truly applies in this case. But, to be clear, had the diving action clearly started in the field of play, that should be administered as a live-ball foul, with 3 & 1 enforcement, thus, canceling any apparent score.
#92, IMHO, for what it is worth, your judgment was correct, based on the supporting video evidence. Perhaps your explanation above was mis-stated, in that you simply conferred with the B, and advised him that you had a great look at the play, and there was no actual grasping of the mask, thus, he conceded and voluntarily decided to retract the foul call. As Rulesman alludes, that is the correct process, and should be used very sparingly - only in instances where you can be sure the retraction will be supported with video evidence. I had such a circumstance once during my collegiate career (S, at the time). I had a great look at a play in which our B flagged a DPI. There simply was no material restriction. After the play, I went to the B and advised him that I had a great look at the play, and there just wasn't anything there. He said he thought he saw an arm grab, but was somewhat screened by the bodies. Upon my assurance that there was no material restriction, he advised the Referee that there was no foul. Our coordinator applauded both of us for getting the call right.