That's a neat trick. You can auction stuff for free by having someone report it as a copyright infringement after the auction is over.
In your auction you said your didn't sign an NDA so you thought maybe it would be bad if you had. Someone that had it to begin with probably did sign something about not passing it out to the public. You just ended up with it somehow. The original recipient selling it and you selling it are tantamount to the same thing. Or, it could be that they thought it was something that they legally had to come down on or risk losing their copyrights or something. One email to ebay is easier and cheaper than having to go to court to get back some IP you lost because you failed to protect it.
