The driver's side bearing, unlike the passenger side, is lubricated by the differential fluid. So the odds of it going bad are pretty small in my opinion. Plus you found no evidence in the drained fluid or with a magnet of heavy wear.
The hub bearing assemblies are known wear items and go bad regularly. Plus, even though bad, you can seldom feel anything wrong when spinning it by hand.
So, I would agree that you should change the hub bearing first. That's what I'd do.
Just to be sure it is not a tire, I'd rotate them first to be sure it is not your left front tire.
3.73; G80; Bose; XM; DIC