My Frigidaire PLGS389ECD slide-in range emits a rapid sequence of 2-10 beeps when I press certain buttons. The number of beeps seems completely random. For example if I press "bake" - it beeps once. Then I enter "350". Pressing the '3' might beep 5 times, pressing '5' might beep 8 times, pressing '0' might beep 4 times. The oven seems otherwise fine, cooks food, etc. There are no error messages on the display. The beeping is brand-new behavior. I baked dinner - no problems. About 2 hours later I turned the oven on to bake bread, and it started this behavior. Unplugging did not help.

Any idea what might be going on, and how to fix it?