Lint in Literature: Freud's Mistress

I came across the word lint in the latest book I'm reading, Freud's Mistress by Karen Mack and Jennifer Kaufman. Here's the passage (Martha is Sigmund Freud's wife):

As the noise level rose, Martha flitted back and forth into the kitchen, checking on the biscuits, the beef, getting this child a glass of water, that child a napkin, removing an elbow or a leg from the arm of a chair, and, at one point, bending over and picking up a wad of lint from the floor.

I like his book, but in places it reads like a history lesson. The story is based in fact but is a historical fictional account of Freud and his sister-in-law Minna, who many feel had an affair.