True. I got jacked up there last year: we had already gone through security to our gate, but had so much time before our flight, we decided to go back to the main terminal to check out the shops. (There are some GREAT stores there: Pendleton, Made in Oregon, Norm Thompson). We brought our drivers' licenses, boarding passes, and credit cards with us.
When we came back through, I set off the alarm. I tried to explain that I had been through there 30 minutes before, but to no avail. Turned out it was my shoes! When I asked why I didn't trigger the alarm the first time through, they explained that the scanners are NOT ALL CALIBRATED UNIFORMLY!!
Gee, that sure bolstered my confidence about the accuracy of the system. Can anyone say "Richard Reid?:"