If you are using the Windows 10 Technical Preview, you may have had a few updates tonight. One of them is a Flash security fix to build 9926, and another is for the Windows 10 Technical Preview (KB3035129).
Interestingly, some users are also getting notifications for a 9931 and 9932 OS update. While at first this seems like good news as it implies new features and fixes, truth be told the update is meant for internal Microsoft testing only but it had been accidentally exposed. As a result, those attempting to install the update are met with a failure to install due to not having the proper credentials.