I saw this same thing happen in rheas crater (leaving from seafarers headed north) on the stair case there is an npc. I think his name is Tin.
Me and a friend of mine were dual tanking and 5 man hench teaming the area. We (sister tai, gita, daemen, herself and I) headed down the stairs to aggro the first group. Now when we run hench generally we aggro wait for wars/asns to approach then she or myself holds their aggro while the other runs ahead to take out rits/monks/.
About half way down the stairs which are zigzagged or staggered sits "Tin" the npc. At this group I run ahead again to take out the rit and monk. She stayed back holding the asn/war aggro of the afflicted.
I did away with the rit/monk fairly quickly and then started in on the mes and ele. Now usually once I have eliminated the monk/rit the wars/asn's start falling as she is working them down.
However, I noticed the hench team taking alot of heavy condition damage (deep wound/bleeding) to which the healers and daemen fell victum and died. I quickly finished off the mes/ele and ran up to her location with the asns/wars.
Two wars and 1 asn was still fighting her. I started in on the asn and Im noticing he is recieving heals. I scan the area and see "Tin" on the staircase using heal area and Jameis gaze I believe on the Asn.
His heals were not efficient enough to counter our damage and we finished the group off but what a stupid glich that is and hopefully we dont see this in other areas more often.
If that is the case then they may as well let us just kill them also.