So I got hired thugs waiting outside the inn yesterday to teach me a lesson. After I'm done wiping the floor with them, I found a note that said Sorex Vinius sent them to teach me a lesson for stealing (I don't remember stealing, but that's fine). I do nothing about it because I'm a Paladin this playthrough. Well, a few in game days later, I'm coming out of a dungeon weighed down with fat loot when some a-hole Khajiit comes rolling up with dual wield daggers and tries to carve me up like a holiday ham. After I beat him down, I find a db contract on me. No name though. Do you guys think it was the same guy who sent the thugs?

No. The DB assassination attempts are just a random event.

From Sorex Vinius you must have taken something though. Perhaps you plucked some deathbell flowers in that inn of his father? Or you took some coins that were lying around in that inn.