Several months ago I received a new Mac Mini from my employer with a pre-release version of Mountain Lion in one of the partitions. Running in the pre release, I went through the App Store and purchased the release version of 10.8. It downloaded the 4Gb in about 3 hours. It then copied some files, then rebooted and seemed to go through the installation process for over 30 minutes. The normal login screen appeared. Going back into App Store, it shows 10.8 with the download button, so it seems that the install hasn't worked? Shutting down, rebooting and restarting several times has not helped.
The apple menu / About this Mac / More Info / shows: Software OS X 10.8 (12A269)
http://en.wikipedia.org/wiki/Mac_OS_X_v10.8#Release_history suggests the build is 12A269 (GM), but I don't know if the GM is significant.
Is this a concern? If so, how can I download and install the final version of Mountain Lion from the App Store?