I would have thought this would be a bit too paranoid but I just read this New York Times article -
Mark Zuckerberg Covers His Laptop Camera. You Should Consider It, Too. - from yesterday talking about that tweet on the picture of Mark Zukerberg next to his laptop, observing that he had the camera and microphone covered.
The scary part of the article is how easy it is for anybody to record you by remote access: 'The taped-over camera and microphone jack are usually a signal that someone is concerned, perhaps only vaguely, about hackers’ gaining access to his or her devices by using remote-access trojans — a process called “ratting.” ...
The practice is fairly technologically simple: Hackers trick people into clicking on links or unfamiliar websites containing malware that allows them access to the devices.
If it's this easy to start recording people in their own home via their laptop camera, would you consider covering that camera?