Huh. I didn't realize that airline had to participate. That's really silly as all they do is print someone on the boarding pass.The other problem (at least right now) with PreCheck is that not all airlines participate in it. Frontier and Spirit are the big two out of MSP that I can think of, though there are surely others that don't participate.
I wonder if I can show TSA my Global Entry card and get in the precheck line even if it's not on the boarding pass.