Everything Pap stated is spot on, especially the place or start in neutral trick for about 10 seconds before placing the tranny in drive or reverse and / or adding 1 additional Qt. of ATF+4 fluid to the tranny. One or the other or a combination of both should solve your problem.
Tranny filter and oil change is not a bad idea either if it has not been done lately!
These transmission dipsticks are notorious for not reading the correct oil level. Low oil level can cause the pump to suck air and make foam which will cause a hesitation at startup....

I run mine about 1/2 inch above the Full when Hot mark at all times with no hesitation at startup...

_________________
Supporting Vendor and Moderator of LOST05 Jeep Liberty CRD Limited 
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount98 Dodge Cummins 24 Valve