I just got a MBA 13" with 2GB of RAM from the Refurbished store yesterday. I realized, a little too late, that I should get the 4GB RAM version in order to future-proof my purchase so I called Apple asking for a return label for this MBA and ordered the 4GB RAM one last night. I'd really like to take this MBA out on a test run today in school but I don't want to be charged a restocking fee, esp. since I have to register the product in the start up screen! If I use it for a few days until the new MBA comes, will I be charged a fee?