Wireless-Powered Piston

What I expected to happen was...:
When I put a redstone block on the top of the piston facing up then I turn on the lever then turn off the lever for some reason the piston stays the same i mean it stays powered.
What actually happened was...:
I was making my own redstone clock using piston Horizontal then recreate to vertical then I use it to make a Dropper Elevator (Item Elevator) then the piston is buggin out then I try to fix and it didn't work so I went here to report this bug.

Steps to Reproduce:
1. Put a piston Block Facing any direction
2. Put an air block on the top of the piston block
3. Then put a redstone block