Having a valid SSL Certificate for your site is important, but you still need to to make sure that users, and search engines, see the secure version - and only the secure version.
Any attempt to access your site using a http address should receive a 301 ("Moved Permanently") status code and be automatically redirected to the equivalent https address.
SiteSentry will scan your site throuhgout the day, checking that an attempt to access it using a http address is redirected to a https equivalent. If successfully redirected, SiteSentry will show you the redirect path. If not, SiteSentry will send you an notification.
This check is a great complement to the SSL Certificate Expiration check, which ensures that your site has a valid SSL Certificate in place.