My trans was doing the same thing when my 08 was new. Everytime it sat overnight, I would start it up, let it idle for 10-20 seconds, and then start driving. The first 1-2 shift was very harsh.
After that, the rest of the trip, no other hard shifts.
I called the Chrysler engineers for advice as to where to begin, since it was new, and had no DTC's stored.
They told me to go in with the WiTech and reset the variable line pressure counters and perform a quick learn. This resets the CVI(clutch volume index) stored in the TCM.
Since then, it shifts like a dream. The engineer I spoke with stated that this was a common condition with the 42RE trans.
My suggestion, if it is under warranty, is to take it in and have them reset the variable line counter and perform a quick learn. You may also want to have the filter and fluid changed while you are there as well.
Hope this helped.