Dunno what made me think of this just now. When I worked for IT in a school district way back in the 90s, a librarian told me she kept a supply of mouse balls in her desk because kids would steal them out of the school computers. What I remember about those balls was they picked up dust and crud off surfaces. Pretty soon optical mice came along and they were history.
Youre mom probably wondered why her mouse started working smoother.
I always keep an old toothbrush in my pencil cup for cleaning the mouse contacts. I dont use a mouse, I’ve always used a track ball, and now and then you have to pop out the ball and clean the accumulated crud out of the contacts.