Gafford exited to the locker room during the second quarter of Tuesday's game against the Bucks after appearing to suffer a right arm injury, Eddie Sefko of the Mavericks' official site reports.
Gafford suffered the injury on a block attempt, and he wasn't able to move his right arm on his way off the court. He can be considered questionable to return until the Mavs have an official diagnosis for the big man.