In the second quarter of the San Francisco 49ers’ showdown against the Seattle Seahawks on Thursday evening, 49ers running back Jordan Mason suffered an apparent left shoulder injury. Mason headed to the locker room almost immediately after reaching the sideline and will reportedly undergo an x-ray. Mason is questionable to return. Before leaving the game, Mason was off to a hot start, boasting a game-high 65 rushing yards on eight carries. Mason has been pivotal to the 49ers’ success this season, with a team-high 536 rushing yards and three touchdowns through five games. CLICK HERE to go to P…