In my experience with PreCheck is that having GE is a guarantee for domestic flights IF you do everything correctly...your PASSID is associated with your itinerary, and your name in the TSA secure flight data on that itinerary matches your GE registration.

My very first time attempting PreCheck (with United) I also didn't get selected and I was peeved about it.. I had put my PASSID
number in my UA profile..but I had neglected to be sure that everything matched up on my itinerary including my full middle name. Since that time I'm 100% successful getting PreCheck because I'm diligent about dotting i's and crossing t's. I'm not familiar with AA's procedures..but it's got to be similar to UA's.. I'd read the PreCheck thread in the AA forum and learn how it works with AA.. it takes a little effort to get things set up but once you do you should be good to go. Also.. if you use a corporate booking engine such as Concur for business travel..be sure your full name and PASSID number are in your Concur/booking engine profile so it gets attached to your reservations.