The hotspot should be 85 but I don't agree that it is fine if it is getting hotter. Kings like it in the cooler side. Quite often you find them more on the cool end of the tank even when the hot side is a good temp. Now if it is going a little bit above 85 every few days or so I would say it is not a big deal although it should still should try to be stopped. But if it is regularly 86-92 then that is not good.