It's funny how quickly people will boot you from their friend lists!
Everytime I make my leader anyone who isn't one of my 6*s for more than 30mins or so I'll lose at least one person. lol.
Come on people... there are very legitimate reasons for why you might have a low level char as your leader. Not my fault the game forces it to work that way.
(not a criticism against GAF, I have quite a few non-GAF friends and randos on there, too)
Unless you don't have GAF stated in your message, I don't think gaffers will delete you just because you didn't have a 6*.
Most likely it's one of your random friends.