Tranmission fluid on top of transmission, could it be blowing out dipstick on 2002 Chrysler Town & Country

I have noticed that when I go through the mountains the next day I have trans fluid on the top of the trans case. Mechanic said no leak on the bottom, could be from lose dip stick. The transmissions shifts fine and seems to be working fine otherwise.

possible vent issue with rezevoir. air pressure change and heat from driving through the hills maybe. did you get a diagnostic run?
Yes, the trans was rebuilt as a result. Thanks for your help.