The NFL did not specify what the gesture was, AP reports.
However, Lynch was seen grabbing his crotch after scoring a touchdown during the overtime win against Green Bay.
"I feel embarrassed to work for a particular organization that fined a teammate of mine for shaking my hand after a touchdown," Lynch tweeted Thursday apparently in reference to Seahawks receiver Chris Matthews, who also received a fine.
Matthews was reportedly fined $11,025 for grabbing his own crotch after the touchdown, according to USA Today.
Lynch was fined $11,000 in December for making a similar gesture after a touchdown run against Arizona.
Lynch was also seen on national TV standing on the sideline grabbing his crotch to celebrate a pick six by teammate Kam Chancellor during the Seahawks' wildcard playoff win over Carolina. No discipline has been announced for that incident.
Not sure what it is about Lynch and his crotch, but you'd think there would be other ways to mark a happy occasion -- like, I don't know, smiling or cheering or jumping up and down -- that are less likely to offend people and save him some money as well.
Lynch's fines are starting to add up. He had to pay $100,000 in November for repeated violations of the league's media policy.