There wouldn't be any health concerns associated with what you grow in the soil that would affect its suitability as a foodstuff, and the mold itself probably is of no concern to the plant's health. The question is, was the soil allowed to go through any significant anaerobic (without oxygen) composting? If it has, there will be a higher than normal concentration of organic acids in the soil, which means a very low pH, which can have an influence on plant vitality. You can take a 'wait and see what happens' position, spread it on the garden/beds/compost pile, or mix it with other media known to be sound to minimize any potential effects.

Al

If moisture didn't get in where you stored it then possibly it had been sitting in the sun previously and the existing moisture in the bag was driven to the top. With no air circulation or possibility of drying out the mould would have made a start. But remember, it will be mould which was already in the bag, only it got a jump start on all the other micro organisms. If you left the affected soil in an open airy place with a bit of moisture the micro organisms will sort themselves out and get it all back into balance.

But as the others have said, make sure you don't breath in any spores from the mould. And that's the same story for any bagged potting soil that has dried out as well. In drying, all the moulds produce spores which then drift around like a fine dust when the soil is disturbed. If you breath that in you can get what is often called "Farmers Lung"

All soil has mold/fungus in it. It is part of how soil works to bring nutrients to the plants roots. Whether it plays a useful roll in potted plants is debatable but it is still a part of what is in there. You can remove the mold but what hasn't grown large enough to see will still be in the mix. You can just mix it in with the rest of the soil and as it is exposed to fresh air and dries you usually won't see it anymore.

While it is always a good idea to avoid breathing in dust from anything, every cubic centimeter of air on this planet has mold spores and many other microbes in it so there is no possible way to avoid breathing some in.

Hi....
mold grows in cool damp places...so take the soil and dump it on a tarp or something in the sun and no more mold...
I have mold growing in my flower pots in the winter after I first water my plants because I have been told its so much cooler in the house....the soil is fine......linda

my store bought bags had white looking stuff on it like mold i still used it didnt even scrape anything off dumped the whole bag into my pot and put my cannabis plants in lols they are doing awesome 10 wks veg out door now in pre flower all 5 ft plus roots look mint

just realized how long ago this was posted lmfao

Go lighter on your product .......

Al