I'm not entirely sure but it could be a break through bleed. This is just an overload of hormones causing you to bleed just a bit. I had it every day for a few hours after I started taking the mini pill. It was just a little bit of fresh red blood. I have stopped taking the pill and every now and then have notice that I am bleeding a bit. It is quite common in women that breastfeed.

If you didn't have any pain associated with it, I don't think it would be anything major to be concerned about. If you are really concerned though, it doesn't hurt to have a talk to your doctor.

I hope everything is okay. It is scary to bleed without knowing why