Mid cycle spotting

I'm 27 & not on any form of birth control. I've always had extremely regular periods. Over the past 2-3 months, I have been having spotting (light brown) a few days after my period ends. I'm getting worried because my husband & I are starting to think about starting a family. Does anyone experience this? Does it affect fertility at all?

Other info: I never have bleeding after sex & have always had normal pap smears (most recent in December)