Most garages in Castle Pines Village went up around 2001, which puts the housing here at the newer end of what we see across the wider Denver-area service territory. That means you're mostly looking at factory-insulated steel sectional doors, often the wider double-car layout that builders favored in this era, running on two lift cables instead of the single-cable setups you'd find on older single doors. Bigger door, bigger torsion spring, more load on each cable - and two cables means two chances for one to fray before the other.
The failure mode we see out here isn't rust-through from an old galvanized cable finally giving up after forty winters. It's fatigue. A door this size cycles a heavier spring, and the cable drum takes more wraps under more tension every time the door runs. Add in the cold-and-severe climate band this whole region sits in - the freeze-thaw cycling that tightens and loosens cable strands over a winter - and you get a cable that snaps clean rather than one that's been visibly wearing thin for months. Homeowners are often surprised there was no warning.
One thing we won't pretend: we can't tell you which cable is going to go next just by looking at the other one. If one side failed, the other side is on borrowed time, but we can't give you a date.