Things are getting very, very weird in Pittsburgh. Already waiting for star running back Le'Veon Bell to report to the team while he holds out due to frustration with being franchise-tagged for the second straight season, the Steelers reportedly had another star missing in action on Monday. 

According to a report from Ed Bouchette and Gerry Dulac of the Pittsburgh Post-Gazette, Antonio Brown did not show up to the Steelers' facility on Monday. 

Steelers wide receiver Antonio Brown did not report for work on Monday, one day after he appeared upset on the field and left the locker room in a hurry following a 42-37 loss to the Kansas City Chiefs, several team sources told the Pittsburgh Post-Gazette.

It is not clear if Brown's absence was excused by coach Mike Tomlin, but several sources indicated they did not know why Brown didn't show up with the rest of his teammates for meetings and film review.

Also on Monday, Brown responded to a critical tweet from a Steelers fan by suggesting that the team trade him in order to find out if Brown would put up the same numbers with a different franchise. 

That tweet came after Brown was seen arguing with Steelers offensive coordinator Randy Fichtner during the team's loss to the Kansas City Chiefs on Sunday. 

As our John Breech noted on Monday, that was not Brown's only emotional display during the game. The receiver also seemed to let his emotions get the better of him late in the fourth quarter. After Roethlisberger scored on a three-yard run with just south of two minutes left to play, Brown didn't celebrate with the team, instead walking off the field by himself, fueling speculation that he might be upset. 

Later on Monday, after this story had been out for a while, Brown's agent Drew Rosenhaus told ESPN.com's Adam Schefter that Brown's absence on Monday was personal, and did not have anything to do with a request for a trade out of Pittsburgh. 

It is worth noting at this point that Brown was one of very few Steelers to publicly back Bell when he did not show up to the facility prior to the team's Week 1 game, while nearly the entire offensive line and front office criticized Bell in the media. Surely, Brown's absence on Monday will not fuel even more speculation about divides within the team's locker room.