I as well am experiencing such problems with pistons although i am not sure weather or not to report it as a new bug.
(pistons powered with a redstone block forced into place above the now bugged piston, by a non effected stick piston are powering other pistons diagonally and will not retract after the power"redstone block" source is retracted "only will retract after redstone block and others nearby are destroyed" and so not helping my constant testing for a perfect fully automatic sugarcane farm)
If this is a new bug please contact me and i can provide more details and screen shots.

also i can no longer place levers on top of pistons