Linen sheets are known to sometimes shed little balls of lint or fluff. This is a completely normal part of the linen fiber's lifecycle–and in fact means your sheets are growing softer and more comfortable by shedding excess fibres. As a rule of thumb, the darker the dye, the more likely shedding will occur. This is because the dyes that are darker can lead to a greater buildup of fibres in the linen. If your Threads do start to shed, don't worry–it should settle within a few washes.