Weird piston acting when powered diagonally

What I exepted to happen was...:
Flying over the piston would not update it when it's powered diagonally.

What actually happened was...:
The piston updates and gets activated

Steps to Reproduce:
1. Place a piston facing upward
2. Place a redstone block diagonally to the piston
3. Fly/walk over the piston
4. Notice how the piston activates

Not relating to the bug:
Also, When pressing F11 once (to get Minecraft fullscreen), and then again (to not have it fullscreen), the window becomes smaller. Don't know if it's a bug but it's been a while there.