Everyone will get an occasional lead that is not in their geographic territory. This is normal and unavoidable. Oftentimes these leads are ‘free’. When this happens it’s usually because of one of the following reasons:
Facebook has the wrong data on someone (not common, but happens)
That person recently visited or moved from your area but now lives somewhere else
Your ad/post was shared or liked by someone in your area and another person from another area responded to it
The person actually is in your area, but has a property need elsewhere