I was playing around with some redstone, and when I put redstone like shown in the file, the piston would become powered. If I removed the redstone from behind or the top, the piston would still be active until a block update. (by the way there's redstone on the blocks above the piston as well)
MC-77235
Blocks being powered by redstone 2 blocks above it and 2 blocks behind it
Resolved
Duplicate
0
Spencer Park
(Unassigned)
Unconfirmed
Minecraft 1.8.1
Retrieved
Thank you for your report.
However, your ticket has been resolved as a duplicate.
This issue has been linked to the original bugreport: MC-108. You can find or add further information on that report.
Please search before reporting any bugs, as it's likely that one exists already.