Oxidation (and other processes) do affect coffee flavor, and grinding it up increases surface area / exposure to oxygen, speeding that up. Putting it in the fridge seems to also worsen flavor, but the freezer seems to be pretty reliable. Here's a nice video discussing this by a weird coffee person (James Hoffmann): Should you freeze coffee beans?
Also, KGLW, nice!
I've totally had that happen to me before :(
That said, I love my honeywell(?) half-face respirator otherwise. It beats a standard face mask in comfort by a mile. I even got some paper N99 filter sheets + reusable holders for them, which works great and makes it so I don't blow through plastic cartridges.