I got my v3 P2V+ last week and it's working great except for one issue and I hope it doesn't mean an exchange is needed.

When I bring the bird down and let it idle when landed, the idle speed will slowly go up a bit to where it makes me a bit nervous that a tipover could happen perhaps.

I've using the version 3.6 assistant and when I do use the app the 'T' stick is always off a bit think -60 usually.,  The slightest pressure up on the stick zeros it out.   Using the calibration feature and moving the sticks around all directions sometimes I can get the T stick to zero out.   I've gotten it to zero out and the -60 has come back twice now.
I've done the IMU calibration several times even though the software indicated it was not needed.

Do you think I'm going to need an exchange or is there another setting, I see 'norm' next to it but if there is something  wrong I don't want to cover it up like that.

It is recommended to shut down the motors after landing.
Letting it idle will cause the idle speed to rise as the Phantom is still trying to keep balance as its not sure you have finished flying.
If you must let it idle then shut down motors and re-start, it will stay in idle that way until you throttle up for take-off.

If the calibration through the assistant doesn't work, you can try the [size=13.63636302948px]without PC method in below thread:
http://forum.dji.com/forum.php?m ... e%2BControl&lang=en

Why let it idle?  Shut it down, it will save power in the battery and wear and tear on the motors and debris from getting into the camera from the prop wash..  You can always power it on and take off again.