Really disturbing but I need some advice

So I’m 9 weeks post section bleeding still not much ! Doctor says it’s all normal and she’s happy but I’ve been finding odd things in my little bits of blood, I swear I found a little piece of stitching the end part with the knot it looked like .... these are obv the dissolvable ones and I’ve had this as well wtf is this ! Is this normal ? I feel great don’t get me wrong but it’s so odd!