Unmatching Security Certificate?

Is the security certificate used by Xfinity/Comcast for customer email outdated or incorrect?  

I have a paid subscription to Bitdefender Total Security,  which is one of the best internet security/anti-malware programs available.
Whenever I LOG OUT of my Comcast/Xfinity email,  I am automatically redirected by Comcast to  https://xfinity.comcast.net/
 and the following Warning pops up from my security program: 

Web Protection by Bitdefender

Suspicious page blocked for your protection

https://xfinity.comcast.net/

Your connection to this web page is not safe due to an unmatching security certificate.
This means that the certificate was issued for a different web address than the one it is being used for, and you run the risk of exposing your data by accessing this page.