We also have GE. I inserted our Trusted Traveler number on line on our reservation page. We flew business class to Houston on way to Panama City Panama; at Phoenix we had pre-check marked on our boarding passes. Going through the Security, one person was grabbing people from the First Class/ TSA Pre-Check line, yelling them not to remove their shoes, belts, or laptops. I had already done all that, ho hum. I got to the screening point, went through the x-ray, was asked if I had metal in my leg; I answered yes, she wanded me on my knee and told me to go, actually pushed me through. My husband went through just after me; he kept his belt on as the guard at the line told everyone to do. After my husband came out of the xray machine, he was told to remove shoes, belt, coins, etc. He was patted down and had to wait for his belt to come through the screener. Before the pat down he was asked if he had any metal; he said both knees were replaced. So, he got the pat down, I did not, I just got wanded.
In Houston, going into the International terminal, we had to go through security both going to Panama and coming back through. We had GE and TSA pre-check but it didn't matter, since all security is done on the kiosks by questions and answers, then with that paper you go through security. This procedures was for everyone not just Trusted Traveler people. Here, we had to take almost everything off (what I mean, except our clothes). All shoes, belts, jackets, heavy watches, etc. off, and open bags with e-readers, laptops, etc. Even going through the lane for pre-check in Houston, we had to do all this. Every TSA security point is different in different airports. Wonder why they tout the "you won't have to...." and then keep doing what they have been doing the long way, not shorter.
So don't feel bad. They randomly select people based on the spot they see on an x-ray or the ping with the wand.