mid-cycle spotting?

I've been on the pill for almost 2 years now. 2 weeks ago I started spotting randomly and I couldn't figure out why. I thought it was because I was taking my pills a little late because of what was going on, so I made it my duty to take them at the same time every day no matter what. However, the spotting didn't stop. My actual period is on now I think. Has this ever happened to anyone else?