User with uid lower than 1000 showing in GDM user list.

edit

I created a user on my system for a local scanner to use call s2f

when i created it I used the command

useradd -r s2f # to create it as a system account

I can check that user got a uid lower than 1000

[me@mpc ~]$ cat /etc/passwd | grep s2f

s2f:x:990:985::/home/s2f:/bin/bash

but the user shows in GDM user list and in the gui user account editor. UID_MIN is set to 1000

/etc/login.defs

[me@pc ~]$ cat /etc/login.defs | grep UID_MIN
UID_MIN                  1000
SYS_UID_MIN               201

Any one why this is happening?