21 weeks di/di surro twins

I am 21 weeks pregnant with di/di twin boys! I am a surrogate and had my 20 week ultrasound a few days ago! My OB called me yesterday to inform me that I have placenta previa. She scheduled a repeat ultrasound for 1/31 to see if the placenta had moved with growth! Wondering if any mom's out there have experienced this and if you had any complications or if it resolved on its own! Thanks!