Well, "brand new" makes me wonder how many miles. I can tell you 1000 miles on the engine does wonders for how it behaves. I have never really noted the rpms, but going full throttle from a stop on mine usually brings a rush up to about 10mph, then a flat spot, then a surge up to 40 mph and a steady pull after that. I am not sure if that is what you are experiencing. I always presumed that was normal but always felt like the flat spot was a characteristic of the transmission and not the engine. Why I presume that I don't know, I guess just because the engine sounded the same the whole time and I get a weird sensation the belt is "doing something" during the flat spot.
Sorry that is not very technical, but having never peered into an open CVT, I can't picture what is exactly going on at all times.