I was activating a piston by charging a stone brick block with a redstone torch on the side of this block. The piston was directly below the redstone torch. When toggling the state of stone brick block's charge, the piston remained in the extended position, though I expected the state of the piston to toggle with the state of the redstone dust/torch. See attached pictures.

Taking note of the block directly to the right of the piston (in the picture), I removed it to see if it would affect the outcome. As you can see in the pictures with this block removed, it did extend and retract the piston under certain conditions upon removal and placing of the two blocks adjacent to the piston. When removing these blocks in a certain sequence (bottom, then the top), the bug occurs, even without the redstone torch above the piston.

I have seen this bug in creative mode in single player and multiplayer. Also, it occurs when the piston points downward.

Thanks!