Lime should be applied according to the recommendations of a soil test done every 3-4 years.
Typical Maryland soils tend to get slightly more acidic each year. Consequently, for lawns or vegetable gardens, lime does need to be applied occasionally to raise the pH. It is best to apply the amount suggested in a soil test's results. Simply liming an arbitrary amount of lime each year can result in a too high pH or a too low pH. Too high or too low creates conditions difficult for fescue to grow.
Here is more information about liming from our website: http://extension.umd.edu/hgic/liming-lawns