Normal.
It's particularly noticeable if you are coming from a gobs-of-torque-at-low-rpm V8-equiped vehicle, which are normally set to shift earlier and still have enough power on reserve if you suddenly need power. Even though the torque on the V6 is present a low rpm, if you want to get the drivability you get with a V8 from a V6, with a fairly large heavy vehicle, and with 6 speeds to manage, this is one artifact of that.
I have found that even in D you can force an upshift early with the paddle shifter, which I do from time to time, when not anticipating a sudden need for power.
I notice that the friction and throw of the accelerator pedal (its "feel") seems to promote heavy acceleration, presumably to give it the feeling of a vehicle that "wants to go".
This is also an artifact of an automatic transmission vs standard. The auto has no idea when you're going to need power suddenly, so it must be prepared and ready for it at all times - it's a REACTIVE transmission.
A manual transmission, on the other hand is a PROACTIVE transmission, depending on who's driving it. The driver is aware of his power needs before he actually needs them in most cases, so he can upshift, or skip-shift, early if needed, or shift late if more power is required. The paddle-shifting "auto-manual" does allow some compromise between the two, one thing I like very much.
I'll also add the observation that it is easy to drive the Ex in a manner that sacrifices MPG. And I think that is the default condition of someone who just jumps in the car and drives, which might explain gripes of poor fuel mileage. You have to be a lot more conscious of your foot position on the gas and do it easy if you are after best fuel mileage. More so than other vehicles I've driven.
Although I do at appropriate times drive with enthusiasm, I have also been a hyper-miler since my teen years (when traffic permits) and I have a lot more technical observations to make on the Ex regarding that, but maybe that's a topic for another time and forum threads.