How? I didn't get to accept, it just notified me that he had added me as a contact and suddenly I had a new entry in my own contacts list
Or did you mean "I accepted" as "I did not instantly delete him from my contacts"?
Nope gave me the option to add him as a contact, which is the only way I know of to accept a friend invite. Definitely wasn't an automatic automated acceptance...except maybe the entire gdev membership invite he seems to have stumbled onto.