Heard a pop while driving on the highway, windshield started forming a crack from the driver side about an inch from the bottom. By the time I reached my destination, it was almost to the 1/3 of the windshield. There was no typical impact sign of any rocks hitting the windshield, and it started at the very edge, both indicating it was not a pebble but rather temperature change or pressure or something.

First stone to hit windshield cracked it at the edge and crack continued to grow

My CX5 was parked in a lot all day in the hot sun. When I returned it had developed a crack from the "A" post extending 2 feet all the way to the center of the windshield. There is no evidence a a rock chip or any kind of vandalism. It leads me to believe there is a flaw with the windshield.

It simply one day, went to get the car at my garage, there was a crack out of nowhere, with no point of impact. By the time I drove to work its length had increase 3X. By the same afternoon I consulted a windshield repair shop for possible no expensive fixes, but it was too late. They replace it for 200$ less than the dealer would have charged. The shop that repaired it told me "it would appear it is an stress crack", to which the dealer did nothing upon when advised.

on another site, someone in Seattle indicated that the dealer (University Mazda) replaced the windshield without charge. Our dealer said no.

From the net, it appears that it is a "common" problem.

Why doesn't Mazda repair the known incidents?