That's interesting, as far as I'm aware all their sites use a wildcard cert. They just send out emails that they were changing that on November 4th due to the current one being a Symantec one (changing to QuoVadis). I noticed just now that https://www.webex.com is already on the new cert.
The Symantec cert expires April 2018. Do you have Meeting Server on-prem maybe?
