Are you sure it was dead?
C fasciatum slings like to play dead, I've also had a scary experience with my C fasciatum sling once, I even rolled it up and down but nothing, I almost discared of it untill I remembered Snarf telling me that they like to play dead, and I left if alone for a while, and to my amasement it jumped up and ran around just a couple of minutes later.
They are sneeky buggers those guys!
I also had another experience with a C afsciatum sling were it was laying stiff as you can get with its legs stretched out, I also moved it around, but nothing. A few mintures later, it was molting.
You never know whith these guys.