Linen has natural thread thickness variations which may appears in the form of nubs and slubs. This is completely normal for linen and hemp threads and does not cause any safety issues.
Linen and hemp will feel rough when they arrive to you in loomstate. They must be washed in order to soften up! Don't judge this book by its cover! It will be fluffy soft after a wash on warm, dry on low, and then steam iron!