I think that I may have found a bug that will kick you out of a battle without respawning the pet. I'm hoping that one or two of you might be able to replicate the situation and see if the outcome is the same.
My Tale of Lament (i.e. The Situation): I was in Mt. Hyjal, running around Nordrassil trying to find the rare Grotto Vole (the last rare pet I was missing in the zone) when I started a battle against a Silky Moth. The moment the battle started I had a massive heart attack (it's a figure of speech). There it was - the rare Grotto Vole. So I downed the moth, captured the vole, and was just about to finish off the last pet when I was suddenly (and violently) kicked out of the battle and put in combat. I was greeted by a hordie (I'm alliance) who was fighting a cultist. When the cultist was dead, I was out of combat. (Note: my server is PvE and I wasn't tagged for PvP at the time).
What I think happened is that the hordie was doing the quest where you feed the faerie dragons berries and they expose cultists for you to kill. I think that the cultist was spawned either on top of me or very close by and somehow it aggroed on me for a second, which kicked me out of the battle. (It didn't actually attack me - or at least my combat log was blank when I checked it). The odd part of the whole thing is that the moth didn't respawn like it should've - which caused my 2nd heart attack (again, just a figure of speech).
In summation (i.e. TL,DR) - Can one of you start a battle anywhere around Nordrassil and have another person work on the Inciting the Elements
quest nearby you and see if you get kicked out of the battle?
Now to go back and try to find another rare Grotto Vole...