If you look at his completed auctions, you'll see he had this chip on the 19th. Here's the auction:

http://cgi.ebay.com/Sky-Harbor-Casino-Lake-Tahoe-25-Chip_W0QQitemZ290402168678QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item439d516f66

Perhaps he accidently sent the wrong chip to you and yours to the guy that won the Sky Harbour.

Email him and politely inform him. Chances are it was an honest mistake that many of us have done.