I'd be less apt to believe faulty glass or the whole pressure theory. I'd be looking into whether or not there is enough expansion area in that window frame. Look closely at the window gasket to be sure it all has equal amounts of "cushion" all the way around the frame. Be sure there are no areas where the gasket is bunched or smashed too tight (with some of the recent horror stories I've read lately about lax quality control on these new trailers, it's worth a look)
Every morning when the sun comes up, I sit and listen to the expansion of the Airstream body while having coffee.
2013 Ram Power Wagon 2500 4X4 5.7 Hemi
2001 Airstream '34 Limited
Fulltime in 2013 and LOVING it !!