Birth Control

I have been on ortho-tricyclen lo for a year now. My periods have always been regular, and I have had no big problems with it since I started. About three weeks ago I started my cycle on time, and six days later it ended. Needless to say, I had intercourse with my finacee. Four days after my cycle ended, I began a light bleeding. This has never happened before. The bleeding lasted about four days, and ended as suddenly as it had started. When I first noticed the bleeding, I quickly checked my pills and realized I had skipped two active pills. Is the bleeding normal, or do I need to worry about getting a pregnancy test in the near future?