Lovely Long Legs

So, first I thought the spider had an hourglass pattern on its back. But then when I looked closely (put your mouse at the bottom of the photo and click on the magnifying glass) it seems like he is shedding his skin. Anybody know anything about this? Do spiders outgrow their carcasses? It also doesn't seem to have enough legs, but when I got too close that didn't slow him down any.