Randy,
I don't now why the mask package would be open, but if the filters that are supposed to be organic vapours package was open, I would return them. Organic filters absorb chemicals at all times while exposed (while not in use), so they are somewhat used if the package was open, and you don't know for how long.

Are they an all in one filter? - vapours and particles. I prefer to interchange seperate organic vapour filters with particle filters on my 3M masks so I do not over expose my organic vapour filters.

As for storing them, I always keep mine in a zip lock bag and I have been able to use them for over a year (quite often in my shop) and they are still going strong. In fact, I can't remember when I replaced the sets that are in use.