It shouldn't be puffy.
I'd bought a container of lunch meat and had stacked it and a few other containers of lunch meat on the right side of the lower shelf of the fridge. A few days ago I was grabbing some of the meat on top of that meat (stay with me here) when I noticed the stack was wobbly. Well-stacked containers aren't supposed to wobble. Why was it wobbling? The lowest container of lunch meat was open. Well, the plastic shell part of it. Because the air inside the plastic bag that actually holds the meat had inflated.
It's still inflated. It's also now very carefully placed in a trash bag that I'll put out soon. Because bag-inflating meat is yet another way Mother Nature says "Do Not Touch."