Subchorionic Hemorrhage

I just had my first apt with the Ob and he said everything looked great, baby's heartrate was 166bpm! As I was leaving, he caught me and told me he noticed I had a small spot of subchorionic hemorrhage and he wants to do another ultrasound in 4 weeks. I haven't had bleeding or spotting up to this point but he said I most likely will have spotting :( I'm so worried! He was pretty vague but said they can go away on their own. Should I worry?!