i've ridden my bike for 7 months now, and that's exactly how it behaves on the highway, down to that you can put your bare hands on the engine, even after an hour of riding. your thermostat is perfectly fine. this is how the bike was designed. be glad, and happy riding!
also, the bike has had 2 services, 600 and 4000, and my mechanic loves money. if there was an issue, he would have mentioned it.