Simple answer - no
More complete answer - no, not ever.
You *have* a three year warranty on the trailer. That covers you at any Airstream dealer. Most of these add on warranty packages come with multiple restrictions.
Story as an example:
Once upon a time I stood in line at a (not Airstream) dealer while spending about $5 or some needed item. Most of my 15 minute wait was taken up by the counter guy reading a long list of repair items on an RV over the phone. Each item went like "needs the fridge door fixed, contacted your warranty outfit, they will not cover it, cost is $XXXX". The items and the prices changed, but the "they will not cover it" pretty much never did.
Put the money in a mutual fund and hope the market doesn't crash or burry it under a rock just in case it does. Either way, $4K will cover a lot of this and that.
Indeed you should carry insurance on your trailer. That's different than a warranty or protection package. Be sure that you are covered on the road, when at a campsite *and* when in storage. You also may want the contents of the trailer covered along with the trailer it's self. Yes, you pay for every single added item in this paragraph.