I'd just like to mention that this is still happening. I was in the Misty Mountains last night on my level 56 burglar and was being attacked by level 46 and 47 grey wargs. (The first one was actually a beryl shard dropper, which was convenient for me as I was going to run right by him.)
Strangely, it wasn't every single warg in the area - I would run through a level 47 warg and nothing would happen, but then other sometimes lower-level wargs were aggroing on me. It happened off-and-on for an hour or two, but this morning I logged on to the same character and it didn't happen once.