Is Having Light Brown-tinged Bleeding During Period Normal?

Hello,

My Girlfriend and I had unprotected sex about 4 weeks ago. I pulled out and didn't come in here or anything, but she freaked out regardless. She bought the "Next Choice" morning after pill and took the following day. A few days later she began bleeding which presumeably means that the pill worked. However, 3 weeks later, on the days close to when her period is supposed to being, she started lightly bleeding a light brown color. Is this normal? and what could it mean? Thank you