Just as a little note, I've also had this problem. It doesn't usually seem to matter where I sign in. It's happened a few times on old accounts and on my most recent account (which is why I had to re-add some of you to a new account).
It is a pain in the ass and I haven't actually found a way to stop it except for not using the account for AGES (don't know if there is some sort of expiry to the add request?