Bleeding at 18 weeks

I started bleeding a bit last night. More than just spotting, bright red but no cramping or other symptoms. Called my OB, she said to go to ER if cramping started, which it never did. Just got back from her office this morning. Had an exam, ultrasound and vaginal ultrasound, all looks good aside from the presence of some brown blood. Baby is moving around, good heartbeat and cervix is closed. Anyone else experienced this? I’m still a bit freaked out.