It's not an "interview", more like going through the formality. They ask very simple things like has there been any change in your marital status, have you ever been convicted of a crime, etc.
They may ask some basic questions about your application to ensure its still accurate and no major changes have happened to your life (or your dependents) to ensure you are still admissible (example: had a baby, committed a crime, etc). Nothing to worry about really.
They may ask some basic questions about your application to ensure its still accurate and no major changes have happened to your life (or your dependents) to ensure you are still admissible (example: had a baby, committed a crime, etc). Nothing to worry about really.