49ers running back Jordan Mason had a great game Monday night filling in for the injured Christian McCaffrey, but when Mason spoke to the media afterward, he was not in a good mood.

Immediately after the game, Mason told ESPN’s Lisa Salters that he discovered friday night that he would start in place of McCaffrey. That would indicate that the 49ers violated NFL injury reporting rules by failing to disclose that McCaffrey’s injury would keep him out of the game. But between Salters’ conversation and talking to reporters at his postgame press conference, someone made it clear to Mason that his comments could get the 49ers in trouble.

A reporter asked Mason, “When did you hear you were going to be in the starting lineup?” and Mason gave a hesitant answer that seemed to blame the media for what he had said on national television.

“That question is exactly why I’m angry,” Mason replied. “That’s why I don’t like talking to the media, because you say one thing wrong, and then you know — I don’t know. Just skip that question.”

But Mason wasn’t wrong to answer Salter’s question honestly. The 49ers were wrong to tell Mason that McCaffrey was out 72 hours before the game, but wait until 90 minutes before kickoff to tell everyone.