There is an EASY FIX for this...
Go to:
/Applications/Utilities/KeyChain Access
Select "KeyChain First Aid" from "KeyChain Access" (menu choice)
Make sure the radio button for "Verify" is selected, and then click the "Start" button.
Once completed, it will tell you if any problems were found just above "Verification Completed".
(In my case "no problems found").
It is not necessary to perform a "repair" if no problems were found, BUT, by doing this, it will STOP the annoying drop down...
"Safari can't verify the identity of the website "static.ak.facebook.com"
a248.e.akamai.net ~ GTE CyberTrust Global Root
"This certificate is not valid (host name mismatch)"
FYI: "KeyChain Access" stores info for Certificates. If a "mismatch" occurs, you get a warning. Doing the above "KeyChain First Aid" will verify and correct the problem.