Why didn't he stop me?

I was sleeping at the top of my favourite comfy chair. It's very tall, but I like to sleep on the top bit.
I can spread out and see all of my territory.

I had my eyes half open, and my human came towards me.

I needed attention and I sensed that belly rubs may be on their way.

I stretched out my front paws, blinked, let out a squeaky meow, rolled over... and fell off the top of the chair.

I managed to sit up, quickly, and pretend that I needed to lick my shoulder clean... but why did my human not stop me rolling over? It's his fault that I fell off.

I stared at him, walked off, and went to sleep in another room.