Gotta check all the hose connections. Often it'll leak after you park it (residual heat from the exhaust further heating the non-circulating coolant). Drive it until really warmed up, park it, and then watch for leaks (especially connections at the tank, the T-fitting below the tank, and the two short hoses behind the thermostat)
One other thing I've learned on the Milano: don't fill to the top mark on the coolant tank. You only want to fill it to around the bottom mark or the seam on the tank. There's not enough head space in the tank to handle the coolant expanding when it gets hot, and if you fill to the top mark cold you will get coolant out the cap when the engine gets hot. This may potentially be your problem.