I had a couple noises in the floor of my 2004, and asked Airstream to look at and repair them on a couple of my trips back to the factory for warranty service. One of mine was more like a load moan rather than a simple squeek, and ran from the bathroom to just in front of the refrigerator. I figured that Airstream intentionally put it there so I couldn't sneak late night snacks with my wife not hearing it.
The fisrt time they tried to muffle the sound by stuffing in more insulation, and the second time the service director told me it wasn't a problem.
The third time, when I was having my vinly replaced (because Airstream put some holes, cuts, etc in it during its original manufacture) the service technician told me that one side of the plywood subfloor had not been screwed down to the frame, and he finally fixed it (under warranty).
Subsequently, now that my trailer is out of warranty, the floor has developed squeeks in a couple new areas, and with the floor secured in front of the refrigerator I've put on an additional 10 pounds.