65 C4 Transmission question

I have a 1965 fully restored Mustang with an automatic C4 transmission. The trans is original but rebuilt with only 2k on it. The car has been parked in the garage for the last month with no problems or leaks, (I faithfully check underneath for leaks). Today I found a steady drip of transmission fluid. I did the usual inspection to find that it is coming from a tube that is at the top drivers side of the transmission. it is a very tight spot to get to but I barely got the camera to to it. If you look at the picture you can see a drop ready to fall. Can anyone shed some light on what my problem is. I really do not want to pull the trans if I don't have to. If you would please look at the pictures and view the small tube dripping, it is circled in red. I would appreciate any help one can give.
Thanks I appreciate it
Dana Wood
woody3882@aol.com

Turns out that the C-4 has a fluid overflow on the top. out of the overflow is a 1/4 "" piece of tubing that runs along the drivers side of the transmission. when the overflow drips it runs down the casing and along the pan gasket so it is hard to figure where the leak is coming from. The weirdest part is, the car was sitting for months with no problems and then one day it just started, It puked out about a cup of trans fluid and just stopped and hasn't leaked since..

As long as it doesn't learn to fart...