TL;DR - It's time to get a new 1lb propane bottle; the current one has a slow leak through the valve.
I've been using the same 1lb propane bottle for something like 15 years. For the first 12 of those, I used it in my shop for my propane torch - mostly for household plumbing, heating up the branding iron I use to mark my woodworking projects, etc. The last few years it has been a staple in the kitchen box, where it has seemed to last about a week or so - usually a whole trip - before needing to be refilled with an adapter from my 20lb tank when I come home.
This time however, when we'd disconnect the 1lb bottle from the Coleman Camp Stove/Grill, there was a slow leak that I couldn't get to stop by shaking or blowing into the valve. Likely the valve spring has simply worn out (finally), so I'll be switching to a new bottle.
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