I'm playing in a Kindle Fire 7th Generation on the 1.6.0 update.

I leave some redstone powered by a Redstone torch for too long and leave my world. I come back and the redstone has the texture of when it's powered off. When I place a Redstone next to it, it's powered. When I place piston, it's powered.

Just acts like powered redstone with a unpowered texture. I fix it by breaking the redstone and placing it again, but it just a bug.