Spotting/Implantation Bleeding??

My husband and I have just started TTC in the last two months. My period is very regular, and I had NEVER experienced spotting in between periods. For the past two cycles, since we started trying, I've been seeing some spotting a few days before AF is due. It looks exactly like what implantation bleeding is described as, and comes right around the time you would expect it, but both months AF has showed up on time, a few days after the spotting has stopped. Does anyone know what this could be, or have you experienced this change to your cycle yourself once you started TTC? Thanks everyone, wishing you all lots of luck :)