Random fires on lot

I played happily with a family in henford on bagley, but when i switched over to another family, and had them visit 3 cobblebottom street, random fires started appearing. Fires are not near stoves, fireplaces or barbeques: they just appeared on an outside wall, the roof and once in the sleeping room. This happened 3 times already, but only when I am visiting this lot, not using it as the current family. For clarification: I do not have any mods, and today is the first time this happens ever.