I thought about the same thing and I'm not sure either. Some of the music sounds like he's still composing music in the 18th and 19th century, which is not at all a bad thing, so it's possible the 18th century style is that "something". It's refreshing to hear this style of music come alive again.
Pleasantly surprised! A friend at work told me about this guy but I expected something different. This music has something that a lot of modern classical music doesn't. I can't quite put my finger on what it is. Excellent work. Wish I could hear the rest of the concerto in c major.