This is to in form you of a bug, maybe, im not sure if it suppose to do this or not. The issue is that, when a piston ether sticky or non, is in a vertical position, and pushes a red-stone block, the piston will not retract, even when the red-stone source that activated it is destroyed, only once the red-stone block that the piston was pushing is destroyed, does the piston retract. this issue happens sometimes in a horizontal position too, i haven t tried it with normal pistons, but sticky pistons have the same issue as the before mentioned, as they will sometimes not retract when pushing and pulling red-stone blocks.

Like i said i dont know if this is a bug, i think it is but i could be wrong, but please look into it.

your fellow MC Twendieal =3