It does sound like they had it posted on another site.  I personally would never do that as it can get confusing and I don't think it's fair to either site's members.  I hope you get the book you want soon!

BTW, I like your screenname :)

Unfortunately this is a common problem. Where people post them on 2 or 3 dif trading sites not realizing, or caring that it might get requested on more than one site at a time.  I spend enough time managing this account, I can't imaging having to keep track of more than one.  Was it a WL book?  It's possible that they were trying to post it directly to somone else and it went to you instead. 

ETA: Missed the no wishers part. It's possible that this person is a boxer and got a BOB offer they wanted to accept right before your request for the book came through.  It doesn't remove BOB books from the shelf until the deal has been agreed to on both sides.