When you win an expired domain auction at GD, the auction takes place during the redemption phase of the expired domain. Which means it can still be redeemed by the current owner.
In your GD auctions account, beside your won domain, you'll see a message telling you when the domain will appear in your account (approximately 6 - 12 days on average). If the owner redeems or transfers their domain before that time, you lose the domain and GD will issue a refund.
Actually, you don't really 'lose' the domain, since it was never yours and it's still technically in the ownership of the current owner.
Happens commonly. In my personal experience, I'd estimate that out of every 10 won auctions of expired domains at GD, 1 or 2 of them get renewed or transfered by the current owner. So I end up with 80 - 90% of my 'won' domains, while about 10 - 20% of the time, the current owner renews or transfers the domain.
It's all part of the TOS for the auctions. Nothing to worry about, just have a good cry, wave bye-bye to the domain, and dive in to your next auction
