Im 12 months postpartum and almost 37. ive noticed the past couple of months im spotting for a few days before my expected flow starts. then my period lasts 4-6 days of flow to spotting at the end. is this cause for concern? no birth control?

This really doesn't sound like anything significant in the absence of any associated symptoms. The total duration of bleeding (spotting or otherwise) is not excessive nor is the amount excessive. Of more concern would be a significant increase in flow or bleeding between your periods. Of course, you may always consult your gynecologist if you continue to be worried.