Coolant was spraying out of the expansion tank filler cap just under the seat. There is a hole in the top of the cap. Shouldn't the coolant system be sealed as I'm sure it builds pressure as it gets warm. The bike is running fine and wasn't overheating at the time.
The cooling system
is sealed if the pressure cap on the radiator is functioning correctly and the coolant expansion tank hose is immersed in coolant. The expansion tank cap is manufactured with a small hole in it.
Your bike seems to be overheating. You haven't mentioned whether you've ever heard the cooling fan operating. How many minutes had you ridden it that day before this happened? Were you in traffic or on the open road?
A properly functioning system would have the fan start before the temperature warning light was lit. If the fan doesn't start, the temp. warning light is lit and if the bike keeps overheating it sprays coolant from the small hole in the expansion tank cap or blows
that cap off entirely with excess pressure.
Take the bike back to the shop soon because it's under warranty. Describe the symptoms. They should flush the coolant system, check the thermostat, check the radiator cap and show you that the cooling fan works and the temperature warning light works.