Why does my iPad connect to my iPhone personal hotspot even though I turned the hotspot off?

I just noticed this and think it's very strange, so thought I would ask here.

I have an iPhone 6 Plus and iPad Air, but running iOS 10.

I was checking my iPad wi-fi connection and noticed that "Doug's iPhone 6 Plus" appeared as a choice, even though I have Personal Hotspot turned off on my iPhone.

Out of curiosity I selected it and my iPhone's personal hotspot turned itself on and let my iPad connect.

That was really strange I thought.

Then I turned the personal hotspot off again and changed the password to see what would happen. I figured that at the minimum if my iPad managed to turn my hotspot on again automatically that at least I would be asked for the password on my iPad. But again it turned the hotspot on and automatically connected - without even asking for the new password.

I think it's weird that the personal hotspot should automatically get turned on like that. Why does that happen? If it's turned off shouldn't it be off?