Just out of curiosity, has anyone else noticed that even on the pill their period sometimes comes late? It's happened to me before and no, I am not pregnant. I take my pill at the same time every day and never miss. My boyfriend and I also use condoms and spermicide and are extremely careful. 
I was 4 days late the last time it happened. Usually I'd start today with some sort of brown discharge. The last time I was "late" I had cramps on a Sunday and started on a Wednesday. Hormones?