Attacked by greys--bug or not?Follow

Here's the situation:

There are gnoll priest assassins and they're out to get to me.

When in Antonica and running between Blackburrow and Sir Yeager[meister]'s Camp, a pair of Sabertooth diviners attacks me everytime. The same thing happens when I go out the back door of Blackburrow (where the "champions" live...in hiding o_O), but it's enchanters out there. I seem to recall it happening with oracles down on the cute little islands off the south coast, but haven't been there for a while so I might just be remembering it how I want to in order to strengthen my story.

Now, I accept that gnolls generally don't like people. They even dislike us enough to try and kill us on sight. Prejudice sucks, but such is the virtual world in which we live. There are, however, a few technical problems with it:
1. I'm in my mid-20's, and they've long since gone grey. None of their grey buddies try to step, just the priest classes.
2. They always appear out of thin air. You're probably thinking it's lag, slow rendering, whatever--which is what I thought the first time. And the second time. After that, seeing as everything around appeared off in the horizon as usual and I never see these priest assassins until I've already run past them and they start blasting, I'm thinking that's not the case. I've stood after dispatching them to see if they re-appear (I'm a glutton for punishment), and they never do...until I try to run through their magical little kill zone, and they step out of the shadows behind me guns a' blazing once more.
3. Once slain, their bodies vanish into thin air. If it weren't for the missing bubble or two of power I had just spent, it would be as if it had never happened. No saliva for me!

I've sent a /bug on it. It's only a minor annoyance--now; they killed me a couple times in my younger days--but still an annoyance. I don't really have a reason to go see Yeager or go into Blackburrow anymore, but my fear is that this could happen other places with more challenging priest assassins. Has anyone else had this problem, be it with gnolls priest assassins or some other kind of priest assassins? Have you guys found buried pressure pads that send a message back to priest assassin HQ telling them to dispatch another pair of stealthy kamikaze clerics?

I am not very familiar with that part of the world, as i am from FP, but what Asura was saying sounds correct, due to the "spawning from no where" effect. Another thing to remember, is that, as you get higher in levels, monsters of a certain con get stronger and stronger. When I was level 7, I could take on 4 blue groups cons, whereas I would not think of trying that now. Seems with each few levels I gain, the things I can solo go down and down (ie used to be white^^, then white^, then white, then blue^^ etc). So, as you are getting higher, the grey cons will start to aggro you, I would figure. I'm not sure that them aggroing you is a bug, but it sounds like their spawn is.

If they are just appearing out of nowhere maybe they are using an invisible spell or something, priests get a spell like that dont they? Havent played yet so im just guessing. Also could it be possible that they are quest spawns and pop once you reach them?