I placed some redstone torches near a piston and in all the normal places it got powered, but it also got power in 2 unusual places..

What I expected to happen was...:
When I place the redstone torch at the corner near the piston it doesn't power it.

What actually happened was...:
When I place the redstone torch at the corner near the piston it did power it.

Steps to Reproduce:
1) Build a 3x2 wall. (Any block)
2) Place a piston in bottom middle of the wall. (Either kind)
3) Try placing a redstone torch at either top corner of the wall.
4) Experiment and watch what happens.