Maybe he saw a ghost :D
My spider did this a couple weeks after I got him(though not as drastically), and then shed out into a bright, banana yellow. He's stayed high yellow for almost a year (he's only gotten brighter :w00t:), so I'm not complaining, but I thought the breeder sent me the wrong snake at first. It's cool to watch them phase like that, though I wish some of those phases were permanent.