Question.. worried mama

So I had an ultrasound on 12-13 and i was supposed to be 7 weeks 6 days according to my LMP. They did it transvaginally, and according to baby size I was only 5 weeks 6 days, we got to see the little baby and see the heart beat, it was beating at a steady 109 bpm- the ultrasound tech said that was because it had started beating only the day before.

Anyways, I work at the same clinic I doctor at. My doctor pulled me into her office on Friday to go over the US results. She said that there was a small subchorionic hemorrhage that was noted on the US. This means that the baby had detached from my uterine wall at one point and reattached somewhere else- causing the bleed. I have not passed any blood.. but she wants a f/I US on 12-26-17 to rule out any potential problems. Until then I am considered “high risk for miscarriage”. Has this happened to anyone else??

*this is my second pregnancy. I have a happy and healthy 2 year old