I started spotting and I am between periods. What can this mean?

Probably normal. Ovulation occurs about two weeks before the menstrual period. At the time of ovulation, the estrogen levels will drop and then continue rising with the cylce. That drop can cause breakthrough bleeding. This is a normal occurence and does not indicate a problem. The fact that a drop in the estrogen level can cause spotting is also the reason women have spotting when they skip a birth control pill.