II alway try to check containers when I shop to see if their sealed , that being said they might not take it back as it’s open .on a good note it might be fine and I’ve found that some lfs especially small ones that don’t get that much traffic will have things on the shelf a long time and just that fact alone sometimes the glue on the seals get old and seal comes off when you open the lid . If it smells and or looks used by all means try to take it back if you can but if it still looks and smell new it probably is it’s just been there a while . I don’t think carbon goes bad unless exposed to air for a while . Ultimately it’s your decision. Good luck !!