I called AmEx, asked them politely why the credit wasn't applied. She asked when it was charged and when I had selected which airline, I told her both were on the 23rd (I waited about 1 h after selecting the airline before I charged). She said it takes a day or so for it to take, but she can manually credit the account after 2 weeks. So I'll call them back on Saturday and request a manual credit. I'll post a follow-up.