I've been spotting for 4 days..

I've had light spotting for four days in a row now. I had my birth control removed a month ago (the implant in my arm) and im not sure if it has something to do with it. Ive had a normal period since then. I am in a monogamous relationship and my SO and I got tested for STDs, all came back negative so I know that's not it. Im not sure if I should see a Dr or is this normal?