Light brown spotting

Hi I'm looking for some possible answers. I'm on BC, next week I am supposed to start my placebo in the pack. For the past two days I've noticed very light brown on the toilet paper. I've always taken my birth control on time going no more than 15 minutes after when I'm supposed to take it. I've been sexually active with my partner for two months. I don't have any other symptoms. I've never spotted before a period is due before. Anyone have any ideas what this could be? I'd appreciate some feedback. Thank you!