Flying with Placenta Previa

Ashley
At my 20 week anatomy scan the doctor said that my placenta is covering my cervix. 80% of them move before birth and it's fine, and I'll get another ultrasound at 28 weeks to see if it has moved. 
The issue/question I have is about my baby shower. My scan is at 28 weeks, and at 29 weeks I am flying to Seattle for my baby shower. If my placenta hasn't moved, will I be told I can't fly? Anyone else had this happen? Does a placenta previa no fly only come into play for later flying?