Oh yeah, as we speak I'm using the Air to download a fresh copy of Mountain Lion 10.8.3 from the App Store. I'll use the InstallESD from that to create a USB installer and do a clean install of ML on both the Air and Pro.
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Sorry. I didnt notice your quote. It turns out the rMBP I bought, was not open-box, it has just went to clearance. All of the box plastics and plastics around the rMBP were still intact.
Don't waste your time downloading the ML with the Air. The rMBP use a special copy of ML and the only way to get it is to do the internet recovery and re-install that way. It won't boot up with the copy you are downloading on your Air.