Just a few data points -

I selected Southwest as my airline and it confirmed (via email) on the Amex site. I then proceed to book two flights for $98.98. Neither one ever caused the meter to go down and did not get reimbursed.

One week later, I booked a flight for $93.98 and after it posted, the meter went down and then it credited. Booked a second flight for $93.98 and am waiting for that one to post/credit.

So, I guess the moral of the story is to give it a few days to properly set as the selected airline. I think I knew this from other Amex cards, but the confirmation came so quick I figured it would work and I didn’t want to lose the fare. Not a big deal as I actually need to take all these flights, but figured the data points would help some one.