Uh, oh, e-bay advanced search indicates that the
seller sold an identical unit (same pics and text) on May 23rd, one day prior to your "Buy it Now" purchase. The previous sale had a "Buy it Now" price of $799. In order to look at what I just saw (in case you are not familiar with this procedure), click advanced search and type in "Vintage Abercrombie & Fitch Seafarer by Heuer", then click the option "completed listings". You'll see both your winning auction and the one from the previous day. Looks like the seller is telling the truth about his error, I'm afraid. Hopefully, for your sake, I'm wrong but that doesn't appear to be the case. . . .
Steve