Welcome to the forum tgger61,
In addition to Hank's thoughts/ideas..... here's some more food for thought.
What was different from day to night? And, was there a common factor on both nights?
Were your windows or over-head vents open at night, and someone in the campground with a campfire burning?? Furnace on at night?... sometimes a brand new furnace will put off a 'burning odor' the first few times it's used. If your trailer isn't brand new, is this the first time you've used the furnace this year?? Any evidence that mice (spiders, bees/wasps, etc) could have set up house-keeping since you used it last??
If your trailer is still under warranty I'd contact the dealer, even if you choose to replace the smoke alarm yourself. The dealer, manuf, & folks who supply the safety alarms need to be aware if indeed these items are failing at less than 1 yr old... if enough people report it, they may issue a service (replacement) advisory.
Hope this helps!
Terri, the Chevy co-pilot