Why are these goblins in the Sacred Pool??

I might be stupid, but I don't understand, and there is no explanation. This is my second playthrough and it happened in the first one too.

I finished saving the refugees. Defended the grove, killed Minthara and the other goblin leaders, with the rest of the goblin camp for dessert. Everyone happy, we celebrate in the camp. Next morning I walk into the Grove, walk up to the Sacred Pool - I see four goblins just chillin' with the druids, standing around. Huh??
Once all see me arrive goblins turn hostile, and the druids suddenly decide to start fighting them. As if they were covering up they were in cahoots all along. And once goblins are dead, no one ever mentions this again. First time this happened I though it was some kind of bug, but second time is weird. And also Kahga is on the floor, passed out next to the pool (I knocked her out but that was inside the cavern, two in-game days ago. she should have come to by now?)

Can anyone tell me what on earth is this bug?