Griffin wrote the word "Heart" on the left side of his undershirt before the game on Sunday. Meant to inspire? Perhaps. Meant to conceal? Definitely.
The "H" was drawn extra wide so that the logo of Nike, which has the official apparel deal with the league, was covered. Griffin has a lucrative deal with its competitor adidas.
Players are allowed to wear logos of shoe brands that endorse them as long as those brands have deals with the league. They are not, however, allowed to cover up the swoosh of Nike, which is in its first year of a five-year deal with the league.
Griffin won't likely be fined because the shirt was only visible before pregame warmups, but NFL spokesman Brian McCarthy told ESPN.com that league officials would talk to him.
"It won't happen again," McCarthy said.
Griffin threw for 320 yards and two touchdowns in a 40-32 upset of the New Orleans Saints.