Hello, Who's there please?

Just wondering what exactly this is..When I drive for a little while in 5th gear..Or keep the car around 2500 - 3000 rpm..A light smoke almost like steam will come up from the shifter area..Like the tranny is overheating but it doesnt act up in any way..I dont know if I need to flush the fluid and replace it or if there is just some oil on top of the tranny case that smokes when its heated up..Just need some clarification and suggestions..Thanks for any help.