A lot depends on your climate and conditions. If it was full of fungal hyphae or had decomposed a great deal, or been invaded by some kind of insect it might give me pause.
It might not be as perfect as new.
Though for me it's something I definitely try to buy on sale and then use for multiple years. I would use it if it were mine. Unless on examination there was something alarming about it.
However, I save my own seed and generally plenty of it. So if something went wrong I could just shrug and go get more potting media.
On some seed that's less picky I wouldn't hesitate to sow into regular potting soil or right into the
native soil of my garden.
Other seed might be precious to me and I might really want to baby it. I'm babying it a bit if I use seed starting mix at all. If it was some extremely precious seed a trip to the store for a fresh bag might happen.
Western Montana gardener and botanist in zone 6a according to 2012 zone update.
Gardening on lakebed sediments with 7 inch silty clay loam topsoil, 7 inch clay accumulation layer underneath, have added sand in places.
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