The league did not specify what the gesture was in the win over Green Bay, but Lynch grabbed his crotch after scoring a go-ahead touchdown in the fourth quarter. Lynch was fined $11,000 for a similar gesture in Seattle's win over Arizona on Dec. 21.
On Thursday, Seattle wide receiver Chris Matthews was fined $11,050, per a league source, for doing the same gesture after Lynch's touchdown. Matthews was the player that recovered the onside kick following Lynch's TD.
After learning about the fine, Lynch put this on Twitter:
I feel embarrassed to work for a particular organization that fined a teammate of mine for shaking my hand after a touchdown— Shawn Lynch (@MoneyLynch) January 23, 2015
However, the fines come from the NFL, not the Seahawks.
From the video, it appears Matthews may have grounds for an appeal. He appears to only shake Lynch's hand, as Lynch tweeted.
Thursday could be just the start of what may be a costly Super Bowl week for Lynch.
An NFL official said the league is considering fining Lynch "significantly more" than the $50,000 it has fined him in each of the past two seasons for not speaking to the media, something Lynch again declined to do postgame Sunday.
This is another issue that threatens to hang over Super Bowl week, with Lynch being required to speak to the media Tuesday, Wednesday and Thursday.
An NFL official said there would be increasing fines for each session Lynch misses, with each fine being more than the two $50,000 fines already imposed and the upcoming fine that is expected soon.
As of now, the NFL and the Seahawks are in discussions about the best way to handle Lynch.
At last January's Super Bowl media day in New Jersey, Lynch spent the session behind a barrier talking with teammates, autographing a football a young fan threw to him, and speaking only to NFL Network's Deion Sanders and to Armed Forces Radio. He ignored many other questions asked from a distance by reporters, and also left for a short while before returning.
Lynch also was told before last Sunday's game he could not wear gold shoes because they were a violation of the NFL's on-field dress code, and that he could be held out of the game if he wore them.
ESPN Seahawks reporter Terry Blount and The Associated Press contributed to this report.