Unusual Denied Request

["Momen, Mazdak" <MMomen@xxxxxxxxx>]

Hi, we have recently noticed unusual denied requests on our Squid servers.
Thu Mar 22 03:00:24 2012      3 ***.***.***.*** TCP_DENIED/403 3437 CONNECT https:443 - NONE/- text/html

We're not sure what "https:443" exactly is or how it is produced. This was not caused by a user, the servers behind our Squid servers are hosting a web application. Any idea what exactly this is?