GREEN BAY, Wis. -- Julius Peppers has worn a different style of shoes for almost every game since he joined the Green Bay Packers this season, and not all of them have been legal under the NFL's uniform and equipment guidelines.

A league source said that Peppers has been fined this season for playing with unauthorized shoes.

Peppers has worn Nike Air Jordans in every game. Most of them were either dark green or black except for the high visibility green and yellow pair he wore in the Week 1 game at the Seattle Seahawks. Those were the same shoes he wore in the preseason. The source said Peppers was not fined for the dark green/black pair he wore in the two most recent games.

Peppers on Thursday acknowledged that he was fined for a shoe violation but said he did not know for which game.

"I think I saw a letter [from the league office] in my locker, but I didn't even really [look at] it," Peppers said.

When asked whether he paid the fine, Peppers said: "They notify the team, and the team deducts it."

Although Nike became the NFL's official outfitter in 2012, not all of their products are on the league's approved list.