Should be normal, meaning exit without error.
Now I had a look the other day, and again today, the only lightdm.conf file I have is very different from yours. Are we talking about the same file ?
The ones on my /Desktop I added myself.
From the wiki page :
# LightDM - light Display Manager
# The display manager service manages the X servers running on the
# system, providing login and auto-login services
# based on gdm upstart script
description "LightDM Display Manager"
author "Robert Ancell <firstname.lastname@example.org>"
start on ((filesystem
and runlevel [!06]
and started dbus
or runlevel PREVLEVEL=S)
stop on runlevel 
if [ -n "$UPSTART_EVENTS" ]
# Check kernel command-line for inhibitors, unless we are being called
for ARG in $(cat /proc/cmdline); do
if [ "$ARG" = "text" ]; then
plymouth quit || :
LighDM configuration is governed by the lightdm.conf file, however it's not suppose to be directly edited, instead use:
Before you start configuring LighDM create a backup file:
sudo cp /etc/lightdm/lightdm.conf /etc/lightdm/lightdm.conf.old