Powered mechanisms react to change of redstone connectivity

What I expected to happen was...:
When I broke the torch the redstone dust would not be powered anymore and nothing would happen to the piston.

What actually happened was...:
For a brief moment the piston became powered.

Steps to Reproduce:
1. Place one redstone torch on a wall.
2. In front of the torch place one piece of redstone dust.
3. Place a piston directly to the left or right of the redstone dust.
4. Break the redstone torch.
5. For a brief moment the piston will become powered.

I put a picture down below to show you how you can set it up. But the piston can also be placed on the right