Piston acting weird when redstone is activated in a specific way

If redstone is laid out in a specific way, the piston stay activated.

What I expected to happen was...:
When the redstone turned off, so would the piston

What actually happened was...:
The piston stayed extended, even tho there was no activated redstone near

Steps to Reproduce:
1. Create a four-block(2x3) L-shape horizontally
2. Place a piston under the far end block of the long side
3. Place redstone over the L shape
4. Activate the redstone on the furthest point away from the piston, which is on the end of the short side
5. When it is disabled again, the piston stays activated