Don't worry about fixed or flexible servicing

I had my second service (18400 miles) at the end of October and  I have driven 600 miles since. The car is on variable (flexible) servicing and after the service, the display showed 20000 miles or 730 days until next service. That was at the end of October but now the service display shows 364 days or 10500 miles until next service. I only do short journeys so the management system computer has worked out the optimum interval time which is far less than the 2 years or 20000 miles the maximum parameters for flexible service intervals.