Tivo keeps tuning to channel I don't get

I constantly find my Roamio basic on channel 9. Nothing broadcasts on channel 9 here. It's not selected in my channel list. I can have all 4 tuners on 4 different channels (Not 9), leave, and when I come home, normally at least one tuner is on channel 9, if not all 4. I live alone, no animals, so nobody is using the Tivo or accidentally hitting the remote. The Tivo is doing it on it's own. Any ideas? No, not really a problem in any way (I haven't noticed any missed recordings because of it), but I'm definitely curious.