I agree that all gears feel a bit more "mushy" in the lower RPM range. It sounds to me like you are having normal synchro issues that plague Nissan transmissions. Mine is the very same way and also has a very "high" pedal engagement. It is my opinion that we will be seeing some upgraded revisions of transmissions in the 370 just as we saw in the 350.
In the meantime, drive the piss out of your car and don't worry. It's under warranty.
