During the pre release procedure, pre-release packages are posted to Joomlacode and made available to the Joomla Bug Squad for final testing. Typically, these packages are not visible to everyone. However, since there are no security issues included in this release, these pre-release packages were not hidden. This caused third party update services such as Akeeba Admin Tools to erroneously report that these releases were available and as such several hundred sites were updated before the packages were hidden on Monday morning.
In the time since then, additional bug fixes needed to be merged to the code base, causing a need for the release packages to be rebuilt. Unfortunately, there have been technical issues during this process, causing unexpected delays in testing and release of these packages.