Are you sure the option "Require confirmation before creating a mobile account" isn't checked on? AFAIK, that's the only reason you'd be promoted when the account is created.
If that option isn't checked, it could be a bug, because it shouldn't be doing that. Also, what OS is this for? Mavericks, or something earlier?

I filed a BR with Apple last year on 10.8.x. The "Create mobile account at login" button unchecked after initial setup even though it was checked prior. Usually one reboot and a re-check fixed it but it was a problem for a while. I have not checked back with the desktop team to see if this still happens after 10.8.4/8.5.