This has been touched upon before by others, but I just want to share my experience, and also thank Henry for the quick repair and retrofit! :)
While setting up camp halfway up Mt. Whitney (Trail Camp), I suddenly found it exceedingly difficult to set the pole tips into their grommets (the first one was easy, of course, but I struggled hard trying to get the second tip into its grommet). Only with the help of my buddy, plus leveraging against a piece of flat rock, did we finally succeed! The next day, as expected, freeing the pole tips from the grommets was completely impossible! I had to cut the webbing strap in order to take down the tent. Luckily, that was our last day and we were heading back to trail head.
Calling Henry after my trip, he explained that silnylon shrinks in dry environments. That made sense, given the low humidity at Whitney that day. Henry further explained that this had happened to others too, and therefore, all new Rainbows (and I believe Double Rainbows as well) now come with a longer strap and a Ladderloc strap length adjuster. Henry repaired and retrofitted my Rainbow with the above ladderloc -- free of charge -- in just a few days!
I count myself lucky that the 'incident' happened on the last day of my three-day trip, since the tent was effectively out of commission once I cut the strap for take down. Owners of earlier Rainbows should contact Henry -- to avoid getting themselves into a potential bind on their next mountain ascend or desert hike!