This stuff is annoying me. I wish Badspot would re-code the game on another more advanced engine. I would re-buy Blockland just for that.
That stuff only happens on certain low-end graphic chipsets. My Radeon 6870 has never seen that effect, but my laptop with a ATI 3200 always has that problem.
It's been happening from versions to versions. It even goe with bricks that have FX effects, I'm surprised that Badspot didn't fix this (or it could be something he can't fix)
You can make a killer "moving elevator" effect with FX bricks though.