Bug in three piston as a water gate. Just see a screen

I create a skill spawner room in surviral and i create a water gate (for increase mobs) but 2 piston have a error in work
In offline and online gamemode i see a this bug.
If pistons off 2 piston on and off in real time (2 positions) if i broke a glitch piston block i listening a sound of turn off piston and piston stay still, not drop.
Maybe (i'm not sure) this bug started in snapshot 12w49a...
This a very serious bug and must will be pached for Redstone Update Minecraft 1.5
In image see details)