[apollo7879]

I have a 06 lacrosse csx with 7800 miles.
I have the same problem that you have.
Like you say it's a minor problem & I haven't bothered
to look into it as of yet.
It must have something to do with the light sensor located
on the dashboard.
You can try cleaning the plastic cover over the sensor to
remove any film that may be blocking the light from getting to the sensor.
( which is something that I will do now that you have reminded me ).