Piston not retracting as they should - redstone issue?

Pistons aren't retracting as they should. Changing redstone BEFORE pistons change their behavior.

What I expected to happen was...:
Piston retracting independently from the route taken by redstone

What actually happened was...:
Changing the position of the redstone wire some blocks BEFORE the piston, changes piston behavior

Steps to Reproduce:
1. Put pistons, redstone and lever as shown in pictures
2. Try to switch on and off the lever
3. Remove the piece of redstone shown in pictures and place it in the other corner
4. Try again to switch on and off the lever