My son, who does not have CAH, had that "dusky" look around his lips as a newborn.  After 5 days in neonatal and 6 months on an apnea monitor they found NOTHING life threatening!  He did have reflux.  He could SPEW across the room!!!!  Anyway, what they thought was sometime this reflux would stop in his throat and cause a short period of blusih episodes!  He’s 5 now and great!  I would ask your pedi about the dusky look!

As to the renin...I have no idea!