Personally, I don't think the spec bump is worth the trouble, but if you're going to try and do this I would just take it to the place you bought it and return it, take the money, and buy the new MBA somewhere else. If you go in trying to exchange it for a newer model, I think you're just opening the door for them to tell you no. Better to couch it as you simply being unhappy with the device and wanting your money back. On that note, you could go in and say that you're irritated that within 30 days the price dropped $100, but they might offer you a gift card or something.
What do you think this fractional bump in speed is going to give you that you can't get with your current MBA?