A student complained that I left my grade book open on my desk, and he could see grades for the whole class. Isn't that picky?

No, actually, it's not. Everyone who deals with protected student information needs to be cautious about "passive" and unintended releases of information. This includes leaving information visible on your desk or walking away from a computer screen that displays student information. We even need to be alert to where monitors are placed, so that they are not visible through a window or doorway.