Will add as a support ticket, but just to warn others prior to fix.....
If you have the DT Reg plugin active that adds a 'Register' button to your events' associated article, then it will still show and that people through to the registration form even when you have the Event set to 'Not Published'
Just updating this thread to confirm this remains an issue with the 2.7.1b package (that's assuming the 2.7.0 Plugin remains the same - I'm assuming it does as the version number is unchanged)