My bet is on the ice maker in your freezer. It has a heating element that runs for a short time before dumping the ice. Here’s a thread I made almost a year ago now. It was only like 4 days after installing my Sense so I knew a lot less of how it worked than I do now. I wish I could rename the thread to something more useful.
EDIT: Actually I see you say it can stay on for as long as 25 minutes, so if that’s the case I doubt it’s the ice maker. Easy to test though. Does it stop when you turn the ice maker off? 