Minecraft up-facing piston/sticky piston pushing redstone block stays on

I expected the sticky piston/piston to pull the redstone block back/retract it's arm when power from the leaver ceased.Although the block did not move.

How to reproduce:
1) Place a sticky piston/piston facing the sky.
2) Place a redstone block ontop of the sticky piston/piston.
3) Power the piston.
4) Remove the powersource from step 3.

Additional notes:
Valid power sources (the ones that I tried, atleast):

• On-state redstone dust
• Redstone torch
• Wooden pressure plate w/item on it
• Stepped on wooden pressure plate
• Stone pressure plate
• Iron pressure plate
• Gold pressure plate
• Wooden button pressed by player
• Wooden button shot by arrow
• Stone button
• Redstone block

I also provided a screenshot.