While I was into about 10 minutes on my treadmill last night, the yellow light came on, on my concentrator, and it started beeping. I turned it off, waited 5 minutes and turned it back on. It's been fine since. Any thoughts on what would cause it to beep like that? I'll give my provider a call next week for their thoughts. Big snowstorm in the Maritimes today so didn't bother calling them.