My first thought was ovulation spotting, but then realized that you're on the pill, so ovulation is being suppressed. It could very well be break-through bleeding/spotting, that is very common when women are using the bcp.
More than likely, this is something benign, but you may want to give your gyn a call just to give him/her a heads up on the situation. You know your body, you know what's normal and what's not normal. The doctor might simply say to monitor the spotting, see what happens next month, and that if it continues, you'd need to be evaluated.
Naturally, if this worsens, if you begin to bleed heavily and/or experience severe cramping, then you need to be seen right away.
Vida
