mob with 0 hp bug

Well, I've heard of players with the 0 hp bug, but this weekend I saw it on a mob.

I was soloing with my level 40 MP. About halfway through a large mission in Stret East, I started receiving ghost damage. I ran for the exit. But before I zoned, my attack pet was able to get the aggro and before long the mob was dead. I looted and continued on. The following mob, however, appeared to be at 0 hp right from the start of the fight. Everything else about the fight seemed normal. The mob didn't take noticeably more or less time to kill than others in the mission. But throughout the entire fight, it appeared to be at 0 hp. So, in this case, the 0 hp bug was merely a visual glitch.

Because of this, I'm thinking that maybe the ghost damage bug somehow sets up the 0 hp bug.

[edit] made a couple corrections