A data loss prevention feature temporarily stores the state of unsaved dashboards and viewlets in your database. If your browser crashes before you get to save or you are logged out after a timeout period, your dashboards and viewlets will be restored upon next login.
Unsaved viewlets and dashboards are marked with a red asterisk immediately to the left of their display names.
Temporary states are deleted from your database when you save dashboards and viewlets, or when you confirm/deny saving in the popup message that appears when you log out. (To log out, click the Logout button located at the top-right of your screen.)