Surprise, Apple released an updates OS X Mavericks Golden Master to new version Build 13A603. Only people downloading it from now on are getting the new build. It seems like the new build and the older build are identifying themselves as the same version.
The new Mavericks build is not available via the Mac Developer Portal or via Software Update. Instead, it is appearing for users installing OS X Mavericks GM for the first time. Additionally, multiple readers have had success installing the new build by re-installing the Mavericks GM over the 13A598 version. It is currently unclear why Apple felt it necessary to create a new GM build, but it is likely built to squash some remaining bugs. Also unclear: which build Apple plans to actually ship and if this new silent 13A603 release is simply an error. [via 9to5mac]