Instant Completion of Act 1 Fairgraves

I was going through acts to pick up passive quests I had missed during campaign. As soon as I accepted Marooned Mariner, my Corrupting Cry went off and somehow killed Fairgraves before I could go find the Allflame.

The quest was marked completed and I was able to claim the passive point, but as shown on my map I had never even entered the zone needed to find the quest item.

https://i.imgur.com/RTdCaKo.jpg