Tested this on my way to work, and my car does the same. I accelerated to 40 MPH and let go of the gas pedal, I can see the car "slowly" decelerate and once it hits 20 MPH a slight bump to 1100-1200 rpm can be seen which to me makes sense once the transmission downshifts to the lowest gear.
I tried accelerating again to 40 MPH and switching the car to neutral, once I hit 20 MPH i didn't see no rpm bump.
I find it in this car that deceleration is much more slower (smoother) than any other "automatic transmission" car I have driven. and I think is due to the CVT transmission. Which attributes to this cars smooth feel while driving. you should not feel the gear changes as you accelerate..