I noticed this tonight on my characters trying to finish Makeb. Monday night I had no issues and was destroying everything in my path. Tonight I'm getting wrecked by silver mobs and I'm taking way more damage than I was just before 3.0. Another thing I've noticed is that on Makeb I would never get dismounted by mobs until 3.0 and now I am always getting knocked off my mount by everything. Kind of annoying!
And yes, I do have GSI active.