just saw this...and you need to check with your provider IMHO
I see you're going to the doctor anyway today--if it's this afternoon you might call and see if they want to see you sooner if the "white flakes" continue. The mucus plug is like snot basically--like bloody snot if you're having "bloody show" also. But white flakes sounds like vernix which should be in your amniotic fluid but NOT in your mucous plug. Any fluid leakage, etc.? A high leak in the bag of waters can "seal itself" (the baby can cover it, that is)...
Although your white flakes might be my snot, KWIM ?