Tua Tagovailoa had fans concerned Sunday when he was wobbling exiting the field after a hard hit in the Miami-Buffalo game. In a recent tweet, NFL Media reporter Ian Rapoport shared the explanation for why Tagovailoa was wobbling at the time but later able to return to the game.

According to Rapoport, Tagovailoa’s back locked up. Rapoport reports that Tagovailoa tweaked his back earlier in the game, but did not have to go out. The hard hit from Matt Milano had Tagovailoa wobbling as he left the field of play.

Tagovailoa returned to the game after being checked out for a concussion.

Tagovailoa’s Dolphins have a 21-17 lead in the 4th quarter of the battle of 2-0 AFC East teams. The former Alabama QB is 13-of-17 for 186 yards and a touchdown.

The Miami-Buffalo game is airing on CBS.