NPC'S disappearing

Hello i didnt want to make a thread about this, i thought it was me, lag or something, but this is already not a coincidence, since the update from AH i've noticed that some NPC's disappeared, but not at all, sometimes i change channels and i found fortunately 1, but sometimes not. I didn't want to report it because 2 of them were NPC'S that make spawn mobs, but 1 of them is not, it's just the turtle from Yahhoy crater, and you got a quest of take him on your back, and arrive some point of the map, but he does not disappear for that. And this is just until lvl 43, i dont know how far it is going.