Radiator Hose problems of the 2002 Cadillac SLS

A "low coolant" light appeared on my 2002 Cadillac Sls (4. 6l northstar VIN-y). While parked steam/smoke (small amount) began rising from the engine compartment and a small puddle of coolant was found below vehicle. Vehicle was inspected and a crack in the engine block was discovered. Mechanic stated this was very odd. Vehicle has 103k miles. Water pump gasket was replaced at 65k miles, head gaskets, thermostat & radiator were replaced at 78k miles and water pump clamp/hose replaced at 83k miles. All these repairs were made by the dealership while the vehicle was under warranty. No other repairs (to my knowledge) were made to the engine/cooling system.