An unusual event occurred, maybe you witnessed it, maybe you're the pilot flying the aircraft next after the event. Could the event have affected the airworthiness of the aircraft? If you're the pilot flying the aircraft after the event, and airworthiness could have been affected, would you like the event to have been reported by the witnessing pilot? If you are the pilot who witnessed the unusual event, is it within your qualification and authority to make a determination if airworthiness could have been affected?