Invisible Piston Bug

I placed a Redstone Torch near a Sticky Piston and the base (not sure what it's called) turned invisible.
You could walk through it, there where no collissions

What just happened
1. I placed a few Stick Pistons with a sblock at the end
2. I placed a Redstone Torch at the 4th Sticky Piston from the block
3. The Sticky Pistion extended and a part of it turned invisible

I don't exactly know how I triggered the bug.
I also have tried to trigger it again but failed