No pistonretraction when triggered from top

When triggering Pistons from top (variable behavior related to signalsource) they tend to not retract when signal is off.
I tested in single player, so no plugin interference!
Watch video:
Mine: http://www.youtube.com/watch?v=GozPy3Qsuko
Also found: http://www.youtube.com/watch?v=y8Faz1901GA

I cannot continue developing something with this bug