Okay, way to worry her, GhostontheNet.
On most forums this would have been greeted with a suggestion to check the usual suspects - stove, toaster/toaster oven, any heating elements (coffeepot?), electrical wiring, ventilation, &c. - here, we also get hauntings, demons, and respiratory infections.
Most likely, though, it was just the ninjas. Ninjas like toast.