Or felt the heat from the oven, especially if her routine brings her close to it. Or just got annoyed at the sound the solonoids make as it cycled on and off to hold the temperature.

But there's a non-zero chance she knew that the human had started doing something with the box that makes things that go in it smell delicious and then got distracted and wanted to remind the human, either wanting to smell some delicious smells or even understanding that that box shouldn't be on when it isn't making delicious smells (from observing other interactions with or around the oven).