Hello, and thank you for using Just Answer. 204 deg. F is a bit high, even if it is a Tier 4 emissions engine. Under 200 would be more the norm.
At 10 hours, all trapped air in the cooling system would have been cleared, so we can rule that out as a possibility.
One possibility is that the fan belts are loose, after being run for 10 hours, they may have seated, and are now under less than necessary tension, check to see if that is the case.
Another possibility is that the airflow over the radiator is being obstructed, check to see that there is no debris blocking the airflow.
And last, The term "worked hard" can mean any number of things, even hint at the possibility of exceeding the limits of the unit, this would cause a higher than normal temperature, however it would not spew forth coolant at an excessive rate/amount.. in other words, a little is to be expected; pints or more, not good and I would suspect engine problems. Bring it back and have it checked out, there should be some form of warranty on a unit this new.