Most soils have a date on them....For example the Pro-Mix order I just got in was bagged 8 months ago....Wonder where its been stored for the last 8 months.
You still have to be careful with those dates on the bag, I purchased some Happy Frog soil a couple years ago and the date stamped into the bag was from 2-3 years prior. I questioned it when it caught my eye, the store owner thought it was weird as well, so he called Fox Farms right then and there to get an answer. Their response was that the soil inside the bag wasn't 2-3 years old, the bag itself was New old stock and was just being used up.
Still seemed a bit odd to me.
Almost every single bag of Happy frog or ocean forest I have purchased has came with fungus gnats.
The first and only time I used ROOTS soil, I ended up with my very first bout of Thrips.