Me too, LB - usually stop on the way home and marvel at the 'light show' - or leave it loaded. I've left my .69 loaded for 3 onths, only to discharge it at the end of the season, previously unfired, - intand ignition and hit centre with that shot - Mink Oil lubed patch, with card wad separating lubed patch from the charge.
Here, a gun is not legally loaded unless capped or powder in the vent. Vent brushed out with a peg in the hole or capless nipple, toothpick in nipple hole - depending on the lube, of course,left loaded until next time. Some are not good for being left a long time.
If I used Hoppe's #9 Plus for lube and had to set the right aside for a week, I'd shoot it off at the end of the day and clean it after getting home. Pretty easy, simple cleaning with just one shot fired - litterally no fouling in the breech at all.
54bucks - on rereading the thread, I see the 'bear season' had just finished, so yes it's time to address the loaded barrel.
I suspect the CO2 machines loose gas over time - and of cour`se, if it's been used a time or 2, along with cold weather, the pressue will be reduced as well. I've seen those things in operation, and indeed, if I had one, I'd probably use it just as you did, to eliminate the having to clean afterwards. We see from what happened to you, that running a worm down first would have been a good habit to get into after 'blowing' a load that has a wad in it.