Though BP does have a tendency to rise with age, normal blood pressure in adults is not age dependant and remains constant at 120/80.
As Rhianna rightly points out, single BP readings are notoriously unreliable and before making management decisions BP is either monitored for up to 6 months or a 24 hour monitor is used to determine if there is a real problem.
160/90 represents modest elevation which initially requires follow up rather than treatment. If you ensure you are no more than your ideal weight, take regular vigorous exercise and reduce your salt intake, you increase your chances of avoiding the diagnosis of hypertension
and the need for treatment.