I think there is also a stress relief process with composites, irregular according to the consistency of fiber and resin. Thus, waves or kinks. Most takes place during and soon after manufacture. Some later, impelled by extremes of temperature well short of softening the material. With an hard-to-replace favorite rod, better be safe than sorry than test the temperature limits that might be endured. Also, keep in mind that rapid changes of temperature, as can happen in a car (20 to 30 degrees in an hour, and back down faster when it is driven again and the AC turned up) are no friend to any bonded assembly of parts because they expand and contract at different rates. And just cork itself is not partial to high heat. So there is more potential damage to a fly rod from extreme heat than just kinking up the blank.
Nevertheless, 'glass fly rods are about as indestructible as can be, one reason we like them.
I left a 60 year old Montague holloglass, a sentimental knockabout favorite, in the back of my car all weekend, being too lazy to lug it to the cool basement after loading up the other car for a weekend trip. A foolish risk that did no harm but could have. But it is cool up here, and we have trees for shade like some of the other New England states. I don't know what they do for shade in Arizona, New Mexico, Texas and the like. The anglers' parking must get very crowded under the bushes out there. They can't all fit under the State tree or walk all the way from the other one.