You could ask the store about it and see what they say. Maybe the stores in your area will have a better response than the ones in my area. The ones around here just brushed it off and refused to address the issue. :idunno
Look closely at that dust on the outside of the bags for any movement...
The Tractor Supply stores in my area have all had a major issue with grain mites for years. They've all been told that the feed is fine and it's just paper mites, but the bags are not paper anymore and, wow, they still have a persistent issue. 🤔 Anyway, I ended up having to change feed stores...