In Safari, should I be concerned about this prompt for a certificate?

HriniakPosterChild

Member
SoSH Member
Jul 6, 2006
14,841
500 feet above Lake Sammammish
When I connect to theatlantic.com in Safari, I sometimes get the following prompt:
 

 
I have always hit CANCEL. But the prompt keeps coming back.
 
In Keychain Access, I have searched for this certificate. It is in the login keychain, and when I click on it in that app, it reveals a "child" which is my Apple ID private key.
 
Can this be an attempt to hack me? Anyone have any suggestions about how to make it go away?