Thanks for that Ken, that was on my mind too.
Martin is an extraordinary company when it comes to standing behind their very fine products and their warranty is among the best in the business, ever! If the current steward is the original purchaser of the instrument a neck reset or a neck coming loose would be fully covered under warranty by Martin. Even if the original purchaser did not register the warranty initially they can still register it now, after the fact, even long after the fact and if this is still their guitar Martin will cover the repairs under warranty.
We participated in helping a client get warranty coverage 50 years after the purchase and Martin was enough of a stand-up company that they agreed to cover warranty repairs 50 years out and based only on a black and white picture of a toothless 9 year old holding the guitar.... Pretty amazing and as a fan and student of how companies do business it was a very impressive interaction to have been able to watch happening.
As for how a company handles revenue recognition with such a fine warranty I am at a total loss but hey it's very client centric and that is ultimately what really matters!
Disclaimer: Although I will always advocate for Martin authorized service centers and obviously have a bias here since we are a Martin authorized warranty center we don't and won't except shipped in work. I turn it down frequently because we don't want it, don't need it, and believe that customers are best served being served by any of the many other Martin authorized service centers closer to home wherever that may be. The statistics for guitars being damaged in shipping is a crying shame and in no way do we ever want to encourage the carnage that the shipping companies (and airlines) are unfortunately known to leave in their wake....
With that out of the way....
It's unusual for a dove tail to come loose as you are describing Josh. I don't believe that I've ever encountered one like this either. Most of the time repair folks have to jump though our sphincters to get the things apart....
As such step one for us if we were doing the work is to determine if someone else has been in there after the thing left the factory. More specifically I would be looking for or inquiring as to if someone else had worked on the instrument prior.
Martin is not known for their dovetails coming loose on the 18's. There were periods when Martin used a bit more glue than some of us would have liked but a dovetail coming loose kind of sort of defies reason when one has a mental picture of how a dovetail works.
The glue is only there to keep things in place where the real mechanical heavy lifting is done by the joint's design clever as it is. Seems to me that for a dovetail to come loose the neck would have to rise out of the joint with the fret board extension being unglued, etc. As such there may be a break or fracture in the dovetail but as to what would have done that it beats the heck out of me.
I guess that if warranty coverage is not appropriate and you do the work you will soon fine out. Let us know what you find Josh?