My '08 never goes above about 4200 rpm even accelerating up a hill. But then again, I usually back off and slow down once I see the tach crossing the 4.

 

Maybe that's why?

I don't think mine goes much over 3-3,500, (from memory), but that probably just my driving.

 

A few days ago, while playing with my 06 FEH I got
it into a situation where the HVBATT was easily
at 70% as displayed by the NAV system. So
essentially there was no more space to put energy.
I then found myself going down a rather steep and
long hill so I put the "gear shift" lever ( it's
not really a gear shift lever ) into the "L"
position. The rpm of the engine immediately
rose to at least 4000 rpm maybe a little higher.
I think what happened here is the computer figured
it had no regen braking left in the battery and
told the eCVT to put all the breaking load back
into the ICE. Which drove the rpms up to the high
level.

 

What you saw there was the Negative split mode. That's the equivalent of downshifting to use engine compression. They've programmed this precisely so that when you are slowing down and the battery is topped up, the energy goes somewhere.