Placenta previa?

Hi all - just had our 20 week ultrasound and ultrasound dr notes I have "placenta previa" which means the placenta is over the cervix. He seemed really unconcerned and said we will check back at 32 weeks. My regular doc appointment is not until next Wednesday to find out more. Does anyone else have this and how concerned was your doc?? Online reading about it it seems like greater cause for concern than the ultrasound doc let on. Everything else is looking good and it's a girl!!!