Redstone could not be placed on the piston on previous versions. now it can. (maybe intended?) When redstone activates, it activates piston correctly. When the power is turned off and the piston retracts and causes redstone dust to drop. To recreate, I had 3 sticky pistons and 3 regular pistons and placed them on their side to actuate horizontally. I placed redstone dust over the bases. Then supplied power to redstone circuit.