Pistons will become powered if a redstone torch is powered and is 1 block above the piston on the sides or 2 directly above the piston regardless of any lack of connecting redstone or blocks. Redstone blocks work but only when a spacer block connecting is removed or pushed.  Afterwords the redstone block will power a piston that is 2 blocks below it even when moved. If the redstone block is moved/destroyed the piston will remain active until updated. Meanwhile the redstone torch will turn on and off the piston as it does.