Game Mechanics: Charm+Out of Combat regen?

[Handull]

So I was solo-ing the break in to fear [You must be logged in to view images. Log in or Register.] and had some really wierd mechanics happen. Twice charming the same mob it seemed as if the mob was being healed over and over, almost like it had out of combat regen. The first time my pet (the shiverback that paths near the portal) killed the spider behind the portal. His HP would drop a bit and then pop back up. At the end of the fight my pet was damaged though.

The second time my pet was fighting 3 mobs at once and managed to kill one of them. I'm not sure how a charmed shiverback (with 2 FS weaps and DS) could manage to kill an amy war while it was fighting a total of 2 amy wars and a spider in fear. In the second fight I saw my pet taking huge damage and then his HP popping back up again.

It was strange for sure, but that mob is dead now.

[Sunderfury]

Resolving due to age