You may be correct. I’ve seen the mites you’re talking about in worm bins before and have even had them attack young worms as well. It would be cool if anyone here has an entomology background and could chime in. From what I’ve read Tyrophagus putrescentiae is a ubiquitous mite species in soil, stored products and house dust and is also pre-packaged with beneficials as a food source for the predators.
High humidity, fungal growth, presence of seeds / fragments / flours cause populations to rise exponentially.
Some more quotes that may or may not give insight into them
The grain or flour mites are one of the most important mites infesting food and feed products, cereals, dried vegetable materials, cheese, corn and dried fruits. Grain mites proliferate under high moisture conditions and are often found in conjunction with fungal growth. Severe infestations result in brownish tinge over the commodity, called “mite dust” because of the light brown coloring of the mite legs.
Grain mites primarily attack the germ. However, they will feed on other parts of the kernel, as well as mold growing on the grain. These mites are responsible for the spread of various fungal spores throughout a grain mass and into adjoining bins. When present in large numbers, the flour or grain mites promote sweating and impart a disagreeable odor to the grain. Grain mites can cause “grocer’s itch” in humans exposed to the mites. Some persons may be allergic to mites.
At humidities less than fifty-five to sixty percent (commodity at twelve percent moisture content or less) grain mites can not survive.
Grain mites are pests that can feed on a variety of processed or finely ground grains, wheat germ, yeast, cheese, powdered milk, flour, or mold spores. Under hot, humid conditions, very large populations of these tiny creatures can develop rapidly. Female grain mites lay up to 800 eggs on the surface of food materials.