The 2010 models were released in mid-October and refurbished units started appearing in early January. I'm guessing they wanted to hold off until after the holiday season, anyway, but also remember that the first builds of the 2010 MacBook Airs had some issues with waking from sleep, so they may also have had some returns that made the timing work out, as well.
I'd expect that by October we'll see refurbished units. It's after the back-to-school period and before the holiday season kicks off. If you can wait until then, it's a great way to get a Mac. The only thing you miss out on is the fancy box, but for 15% off list, you get a full warranty, and I think it's actually less likely you'll get a defective unit since they are all inspected before being placed for sale. $1400 would be a great price to get the Core i7 256GB 11" model.