No real logical explanation. I felt it was selling quite comfortably for the time being at 30 BTC, but I'm assuming miners sell what they have for dirt cheap just to get rid of it and are constantly competing for lowest price. But the time they spent mining was essentially pointless selling that low. I would rather wait it out than to sell. For example looking at the latest sell on cryptorush, .0006 for a dollar. I believe someone commented earlier, "Oh man I really need to cash out to get that pack of gum."