How did grease get in under cooktop on stove? Even though I don't fry things often somehow there is grease all along the gap between my gas cooktop and the rest of the stove (above the knobs) which I suddenly noticed. The cooktop does not lift up so I will have to clean what I can from the front. 



There doesn't seem to be any hole big enough where the gas comes out for grease to go down so I don't know where it came from. But I do sort of worry since my stove is about 15 years old what if there was plant matter such as garlic in with the grease? Or could this be from cleaning the surface and grease getting stuck in the gap? It's still puzzling since I rarely fry things. And the grease is mostly at the edges of the stove rather than close to the burners.
Most of the dishes we cook do have at least some oils and fats in them. Even when we are not explicitly frying, or even sauteeing, the delicious fragrant vapors which fill our kitchens when we cook waft around and get into every nook and cranny of our walls, cupboards and stoves, even places where we can't reach to clean. These vapors contain tiny droplets of oil from our cooking. Over time, this deposits lots of grease in inaccessible places.

After a few years, even the blinds above the sink on the other side of my kitchen are lightly coated with a gross mixture of dust and grease. I do fry and sautee a lot, so it may take longer in your kitchen, but that's where that greasy residue comes from - through the air.