Phone keeps prompting for pattern confirmation

About two weeks ago, my Motorola Droid Turbo on Android 5.1 Lollipop started popping up the confirm pattern screen for no apparent reason.  It happens like every 10-15 minutes whether I'm using the phone or not. My attention span isn't long enough to time it properly. I took it in to the Verizon store and the guy played with some settings but that didn't help. I watched a process monitor to see if I could see anything spike CPU usage when it happened but didn't see anything. I've tried uninstalling apps but I hadn't installed anything new when this started. I've tried to confirm the pattern multiple times, and when I do it just goes back to the security options screen. I've tried changing the pattern to no avail, as well as setting it to PIN and then back. (I can't set it to no security due to a work app, unfortunately.) Any ideas what could be causing this?