The context of the following conversation is Tracey saw mouse droppings in their house, so they set a trap and caught it.:
Tracy says Be careful where you're walking, I've got mousetraps everywhere..
The friend responds Is there an infestation?.
Tracy responds I don't know, but I found mouse droppings in a few rooms of the house and didn't want to take any chances..
The friend responds That's good thinking. Mice are pests..