Raining Sand!

Ok, I use a testing world for the updates for 1.5, and recently the world corrupted, and so I made another world. This one was okay for the 1.5 update, but after a while, I noticed a teeny little problem. Sand was falling from the sky! It would randomly fall, and stay there, like snow or something. Extremely wierd, and I made a dome over my experimentation station to keep the sand out. Check it out here: http://imgur.com/a/gOIzr