Brown responded to Kittle's tweet, which came a day after reports emerged from Pittsburgh, saying Brown was involved in a disagreement with Steelers quarterback Ben Roethlisberger.
Sources told NFL Network that Brown skipped a Steelers' walkthrough and left Sunday's game at halftime as the Steelers beat the Cincinnati Bengals. Brown did not play in the game And was listed with a knee injury.
Sources told ESPNand the Pittsburgh Post-Gazette that Brown decided to sit out practices after the dispute and he was benched by the Steelers for the Bengals game. The Post-Gazette reported that Brown threw a football in Roethlisberger's direction during the dispute.
An NFL executive told NFL Network that they compare the situation to what happened between the Steelers and former wide receiver Santonio Homes, who was traded during the 2010 offseason.
On Monday, Kittle tweeted "Sup? @AB84."
Brown responded with a star-eyed smiling emoji.
Brown, 30, is under contract with the Steelers through the 2021 season. He is set to make more than $15 million next season.
The seven-time Pro Bowl selection had 104 catches for 1,297 yards and a league-high 15 touchdowns this season. Brown has six consecutive seasons with at least 100 receptions, 1,200 yards and eight touchdowns. He could climb into the top 20 among the all-time leaders in receiving scores if he reaches those numbers again in 2019.
Kittle, 25, made his first Pro Bowl in 2018 after erupting for 88 receptions, 1,377 yards and five scores in 16 starts in his second NFL season.