When using 'Hide Login Page Settings' as below and you logged in status times out (e.g. you don't log out and walk away and don't do anything for a period of time) the pop-up login page that is displayed when you return to do something is the redirected page rather than the actual login prompt.
Hide wp-admin : On
Hide Login Page : On
Access error type : Redirect
Hide wp-admin : On
Hide Login Page : On
Access error type : Redirect