I think it's an area of strong consideration for them. Not a 'gaping' need but still... Sullivan will be 33 in August. Hopefully he's fine for this year and maybe he is for 2019 too. I think the fear with Sullivan is he missed all of 2015 and was a backup in 2016 so can he played two full seasons in a row now as the starter? I think he can, especially if they manage him the same way (not practicing Wednesdays).
But OL depth is an overall issue and even though Blythe did perform well when called upon last year if a quality center is there in the 4th-6th rounds it could be a good investment. Someone that can play center and guard. Maybe Ragnow or Clapp. The center Adams from NC State that Deadpool talked about could be an option. Or Mason Cole from Michigan.