Thanks all for the suggestions. I did put a big piece of cardboard under the car over night and there were no drops. That's why I concluded that transmission fluid is being lost only during driving.
While I was waiting for response to my original post I added trans sealant and after a couple of days the problem seems to have gone away. I know most of you are cringing now, but at 250K miles I was looking for any way to add life to my trans
Anyway to summarize for others reviewing this threat:
* service trans
* consider getting a new dipstick tube
* check if trans cooling lines are leaking
* add UV dye and get black light to trace the leak
* "up your equipment game, or borrow some things asap"
