[Bug] Kill X mobs quest completion

[jitsuk]

I am not calling this an exploit, it may be just a bug.

Today, while doing part of the destany quest line under the Temple of Mitra, I had to save 5 citizens.
I killed the first few mobs at the entrance and was able to save two citizens.
I decided to turn right and jump down to the lower level where I saved 1 more citizen.
I couldn't save the last two citizens on the upper tier because the lower area was separated from the upper by a gate.
I decided to hearth and reenter the instance.
After I reentered the instance, I found the initial 2 citizens were reset but the enemy mobs weren't.
I ran up to them, saved them, and completed the quest.

I assume you can do this for other kill X or save X type quests.
Enter instance, kill to first few mobs, leave instance, come back and repeat.