Your mileage is certainly below the average yearly driving done by most drivers. Car manufactures always give timing belt change intervals based on mileage and years, some engines rather than others are known to break timing belts at or around the timing belt change interval but this engine does not prematurely break timing belts. The down side is if this engine does break its timing belt it does serious damage to the engine. Timing belts fail if they become contaminated with oil (due to leaking seals or gaskets) but the rubber in a timing belt naturals degrades over time due to heat cycling and natural ozone decay. For piece of mind I would replace the timing belt.