I've been out bid literally at the last second and lost items I was positive I'd won ! GRRR!
Congratulations on your first auction win !!!!
The last 20 seconds or so definitely get the adrenaline flowing !
Probably someone using sniping software. I do tend to use it myself, as a lot of auctions tend to end at inconvenient times, so it's easier to let the system get on with it.
A lot of people think sniping is wrong, but there is nothing unethical about it. It's no different to sitting there manually and trying to get in at the last second, which a lot of people do. It saves you time and effort and means you don't get caught up in a bidding war. As long as you enter the highest amount you are prepared to pay for the item, then you won't lose out either way. If you win the item, you may well have paid a lot less than you would otherwise have had to, if you don't win it then whoever did has paid more than you were prepared to.