PITTSBURGH -- The NFL is reviewing the explicit message worn on the eye black of Pittsburgh Steelers wide receiver George Pickens during Sunday night's loss to the Dallas Cowboys for a potential fine over violation of the league's uniform policy, according to a league source.

Pickens' message read, "Open F---ing Always," and was written in silver over the eye black.

According to league rules, Rule 5, Section 4, Article 8 states that players are prohibited from "wearing, displaying or otherwise conveying personal messages either in writing or illustration, unless such message has been approved in advance by the League office."

Steelers coach Mike Tomlin said he was unaware of Pickens' eye black.

"I don't know what messaging you're talking about regarding his eye black," Tomlin said Tuesday. "I didn't have any outlying issue with his effort."

Pickens, who played a career-low 34 snaps Sunday, declined a postgame interview request and didn't make himself available during Monday's open locker room.

Any fine issued for the message is expected to be disclosed in the NFL's game-day accountability report issued Saturday, according to a league source.

The league has a history of fining players -- including members of the Steelers -- for sharing personal messages on game day.

In 2015, Steelers defensive lineman Cam Heyward was fined for writing "Iron Head" on his eye black in a tribute to his late father. That same week, Steelers running back DeAngelo Williams was fined for wearing eye black that read "Find the Cure" to honor his mother and aunts whom he lost to breast cancer.

Steelers defensive back William Gay also was fined that week in 2015 for wearing purple cleats to show support for domestic violence awareness.