There are different additives in different areas which I'm sure accounts for some difference in "storability"
I've had one car that had terrible gas. (87 MR2) The gas didn't even smell like gasoline. More like limestone sludge or sulfur or something. New pump, new gas, started right up.
Had a lawn mower that I got for free. Hadn't been used for 2 years wouldn't start. New gas in the tank and bam, started right up.
Finally got a trimmer this spring. Hadn't been used for 2 years, wouldn't start. Drained gas, refilled, started up first or second pull.
Maybe colorado gets additives that hurt long term storing?