I haven't had any coolant issues with my 1M, but when my 335 was new I had to refill the expansion tank at least once. Since then, it hasn't demonstrated any unusual consumption of coolant. I assumed the car was a bit under filled from the factory.
I would carefully inspect the coolant hoses and couplings for any signs of a leak. Specifically look for any coolant pooled on the splash shield beneath the radiator. If there is no sign of leak, then I would just wait and see if you continue to need additional coolant. The only other concern would be a leaking water jacket from a defective gasket or block which seems improbable given your relatively low mileage.