Odd BUD behavior when a redstone torch is diagonal to a piston

I'm not very good at explaining things but here it goes... I was attempting to build a double piston extender when I ran into this odd glitch. I powered a block that was above diagonally from the piston which caused a normal bud, as expected. but when I put a redstone torch diagonal to the piston and powered it at the same time as the block that was diagonally above the piston it caused the piston to behave as if it was directly powered, instead of acting like a normal bud. Budded pistons will be activated by a diagonal torch in any situation.
What I expected to happen was...:
The torch diagonal to the piston would not affect the bud in any way.

What actually happened was...:
The redstone torch seemed to cause some update to the piston causing it to extend and retract as if it was normally powered

Steps to Reproduce:
This is to reproduce the exact way I discovered it. Redstone torches will update a budded piston that is diagonal to them in any situation.
1. Place a piston down and put a block diagonally above it
2. Place a redstone torch diagonally to the side of the piston
3. Place redstone next to the block that the redstone torch is on top of and run it into the block that is diagonally above the piston. Then power the block that the redstone torch is on top of and watch it happen.
(if that was too confusing just look at the pictures)