I have several stains on mine.
I only seen one when I took it to the dealership a couple of weeks ago for some of their screw ups. They tried to get it out, but now it's just a yellow stain with a water ring around it.
After I got it back (wife picked it up) she said the stain was still there. I told her don't bother, I'll look at it. That evening I looked the headliner over really good, and seen several stains. The biggest one is right above the rear view mirror. I plan on taking it back in next week as I'm going on vacation, and plan to put many many miles on their loaner. :)