Placental Aging????

Crystal
Today I went for an ultrasound, I am currently 36w5d. And the ultrasound tech said my placenta was a grade 3?? I have read a lot of stuff and no where did I read anything about this. And Google has been of no help at all. Has anyone gone through this? I have an appointment with my ob/gyn on Wednesday and I'm just scared of what he is going to say.