They appear to be a legitimate Airstream Dealer.. If so, then most likely trailer is legitimate.. If dealers are tired of looking at it or paying flooring charges, they might well drop price to make it go away.. In Airstream world, traveling 380 miles to get right model trailer at really good price is pretty common, and used trailers will lead people to travel even further. Consistent advice is not to leave, however, until all the potential warranty items you can identify are addressed, as you will not likely want to go back for nuisance warranty items..
Can't hurt to check Airstream corporate website for dealer list to verify status (they list active dealers across US On their site.) and perhaps a BBB or Yelp check as well for customer comments.. (Though Yelp's objectivity has been questioned a lot lately..)
In Theory, there's no difference between Theory and Practice, but in Practice, there is usually a difference...