Anyone have marginal placenta previa?

I just had my 20 week ultrasound and baby looks great, but I found out I have marginal placenta previa-- my placenta is only 11mm away from my cervix. They think it'll resolve itself as the uterus grows and told me I don't need to change my activities as long as I don't have any bleeding (and I haven't at all). They'll do another ultrasound in 4-6 weeks to see if it has moved.