Mountain Lion Recovery Thumb Drive on Late 2012 iMac

I recently purchased a Late 2012 iMac, as well as a Late 2012 MacMini Server. I recently discovered that neither machine will boot off of 10.8.2 Recovery Thumb Drive that I created. When starting up while holding option, I get a Ø symbol displayed on the screen. Also, when I try to re-download Mountain Lion on either machine from the app store, I receive a message that the software is not compatible with my machine? I had already purchased Mountain Lion for other macs prior to purchasing these machines, however, I do not believe that there is a newer OS version for these machines? The only way I could perform any type of recovery was from the internet recovery.

Any ideas?

Thanks