This area sits in a cold-moderate climate band, which means freeze-thaw cycling rather than extreme heat is the usual culprit on steel panels - moisture gets into a seam or a ding, freezes, and the crack grows a little wider each winter until a section finally buckles. On a door built in the early 2000s, that's more often a factory seam than rot, since most of these doors are steel with a foam core rather than solid wood.
The other common cause we see on newer stock like Priceville's is impact damage - a trailer hitch, a bike rack, a mower backed in too fast - denting a single panel on an otherwise sound door. Because the house and door are newer, the rest of the hardware (rollers, hinges, track) is usually still fine, so there's no reason to replace more than the section that's actually hit.