This is standard procedure. Apple does not stop supporting the current OS with its next major release. It supports older versions of OS X going back at least two versions. In the case of Mavericks, OS X 10.9.5 will probably be the last numbered release. However, if something pops up, then it may release a patch that addresses the issue. Even at that, Apple will continue to support OS X 10.8 at least until the release of OS X 10.11.