Apple today seeded build 13D28 of OS X 10.9.3 to developers, a little over one week after releasing the third OS X 10.9.3 beta, build 13D21 and three weeks after the first 10.9.3 beta. The beta is available through the Software Update mechanism in the Mac App Store as well as through the Mac Dev Center.
Article Link: Apple Seeds OS X Mavericks 10.9.3 Build 13D28 to Developers