Probably the ATF fluid drain back issue that's plagued DCJ transmissions since at least the 1s gen mini-vans, ask me how I know the date. Anyway if the problem only seems to occur on a cold (overnight or day of work) transmission then the diagnostic test I'm fond of is 1) crank up engine; 2) shift into neutral (not park as the FSM implies the ATF fluid pump works faster in neutral then park): 3) bring idle up to ca. 1200-1500 and hold for 10-15 seconds; and 4) then shift into gear and drive normally. In my experience the issue seems more obvious in drive than reverse but I've had the problem in both. If after you first try to shift into gear you get a no go or sluggish go immediately shift back into neutral and repeat above.
If this technique makes the problem go away it's fluid drain back and the most common and generally successful fix is a tranny service with OEM or name brand (WIX for example) filters (both of them) and ATF+4 (Note - geordi if fond of adding a Lucas tranny product see
viewtopic.php?f=5&t=69151&p=739813&hilit=+snot#p739813).
FYI I drove with the "problem", using the above technique to be sure the fluid was pumped up, for about 20K miles (from the time I got my current CRD until SunCoast did the TC install) with zero issues. Subsequent to the TC install with new fluid/filter/transgo kit I've had no problem.