Sometimes the line is hard to define. People get followed, but I don't think it's very common especially with malicious intent of breaking into your house to harm you. Have you ever had something like that happen to you, or have you heard about it happening to someone else close to you or maybe it was in the local news recently? If that's affirmative, I'd say it was definitely more of an anxiety thing. Otherwise or without any other reason to believe such a thing was happening I'd say it's more accurate to call it paranoia.