Redstone Blocks And Sticky Pistons

I thought that when you orientate a piston to face up with a redstone block it will extend and retract freely.

What actually happened was the sticky piston would not retract after being extended because the game thinks the extended piston part is a normal block therefor the redstone block is powering it and since the piston is touching it it will stay powered unless you break the redstone block.

1. You place a sticky piston so that it would extend upwards.
2. You place a redstone block on top of it.
3. You turn the sticky piston on then off it will extend but not retract.