John Froschauer/Associated Press

Peyton Manning was reportedly so apologetic for using off-color language toward official Butch Hannah that he sent an apology letter to the retiring umpire.

"He said he wanted to apologize for his reaction to me that day against the Dolphins," Hannah said, per Mark Wiedmer of the Chattanooga Times Free Press. "Would I please accept his apology? That's the only time that's happened to me in all my years of officiating."

Hannah is retiring after more than 30 years as an official and served as an alternate for the two Super Bowls that Manning won during his career. He also got to know No. 18 when he officiated some of Manning's games at the University of Tennessee.

"Peyton's next-to-last year (2014), the Broncos were facing the Dolphins in Denver and the whole game was a struggle for them," Hannah said while explaining the incident prompting the apology, per Wiedmer.

"I called back two Denver touchdowns. But they pulled it out by two or three points (39-36). But late in the game, the clock about to run out, Peyton mistimed a snap and they had to run one more play. Peyton said something off-color to me, which was not at all like him."

The apology letter arrived in a FedEx package after it was initially sent to the NFL offices.

Hannah also said Manning approached him in a preseason game the next season and made sure he received the card.