Well, I was doing the quest in which you need to retrieve Nettlebane, given to me by Danica in Whiterun...
I had just retrieved the sap from the magical tree and fought the Spriggans, and noticed the two "adventurers" who were in that cave had been killed.
So I thought: "well they won't be needing their stuff anymore", and stole some stuff from their bag/satchel.
Some time passed and I was walking in the College of Winterhold when suddenly a bunch of hired mercenaries attacked me (inside the College)...
When I killed them all, I took a look at the bounty which said something like "kill that thief... Asta"... and I was like "who's Asta?"
Turned out she was one of the adventurers that came back from the dead just to get their revenge on me...

Anyone experience something similar?

Nobody coming from beyond the grave to exact revenge on me but I had a quest where you have to intercept a courier somewhere east of Nightgate Inn (if I remember correctly). I find the courier in the wilderness being attacked by a wolf so I kill the wolf. He begins a dialogue with me and suddenly the dialogue script changes to something about being overrun and he takes off at warp speed. I could see him in the distance but couldn't catch him even with using my shout. All of sudden he falls over dead on a path without being killed by anything. I just looted his body and went on my way.

ooh yea the dark brotherhood also sends any assassin out to get you as well i was out adventuring for few days real time in-game time about 30 hours a party of 3 came up on me they asked me to hand over my stuff then this guy told me i'm going to enjoy killing you i was like (WTF) montherF**ker RUN!! LIKE H*LL then after dealing with the party of 3 walked up the road about 200 feet out came the buggy man (Brotherhood Assassin) HOLY S**T what else am i going to find jesus around the next corner.LOL

I always encounter some Argonian assassin from the Dark Brotherhood trying to kill me... Never know why.