Whenever I set a piece of paper or a notebook with paper over my trackpad, it begins to act erratically for hours at a time. By erratic, I mean the mouse jumps around the screen and sometimes even clicks / right-clicks. This has been happening for several years (my MBP is from 2010, late-fall 15" i7).
I've never bothered to take it in, because it usually goes away. It also helps if I vigorously wipe it with a dry cloth.
Does anyone know the cause of this? Is there some type of oil on paper that could be the culprit?