I've looked and can't really find anywhere stating that there's a real risk of (an unattached) gas canister being kept warm indoors temporarily. One mention I have found is on the Scouts site which just states about the carbon monoxide thing (ie. gas not burnt properly causing carbon monoxide).
Otherwise it (also) states about gas (it discusses propane and butane but after finding the MSR has another manufacturer that's even better, I just use that all year round) not being as efficient in super low temps.
https://www.scouts.org.uk/volunteers/st ... afely/gas/
Hopefully we can get some more clarification on this, as to whether it actually is or isn't safe (leaks?) being stored inside the bag (there's no spark so it's not gonna suddenly become 'lit'). I imagine anyone storijg it inside their bag would want to use a high quality canister that doesn't have as much leakage risks associated
The one suggested to me for winter by the (indy) outdoor shop was Jetboil canisters. Which are a blend of Isobutane/Propane, manufactured in Manchester by GoGas/Johnson Outdoor Gear. Reason I included the full blurb/info is that I've found em to be more efficient than the MSR they've replaced and (obviously) significantly better and longer lasting than the cheap Colemans canisters.
Looking forward to some more science on the subject (please).