Sure, we've read about this happening to people from time to time. When our 2011 Landmark was new, the dining light came out of the ceiling. I remounted it, which was pretty easy. I think I used slightly larger screws. It's stayed put ever since.
You can certainly have this fixed under warranty. But if there's no other reason to take the trailer to your dealer, you might have a go at it yourself rather than haul it to the dealer. Best case, they'll screw things back into place while you wait. Worst case, they'll tell you to drop the trailer and come back at some indefinite point in the future.
If you do put them back yourself, if there's a flat surface on the fixture, a strip or two of double-sided tape might be a good idea. Perhaps 1/2" fender tape would assist the screws. Or a little butyl tape.
In any case, you might want to call Heartland Customer Service at 877-262-8032 / 574-262-8030. Have your VIN # ready. They'll put a note on your computer record that the lights fell down. If the problem comes back after warranty expires, they will be more likely to help out at that time.