Betcha ya anything that the metal line wore through from the clamp that attached it to the engine. That's what happened to mine last fall and that's pretty much the same kind of repair I did. As long as they used rubber transmission cooler line, it should be OK -- that stuff is rated for more pressure and temp that the transmission oil is likely to have on these cars and is designed to withstand ATF.

You can read all the details and see pictures of the damage the flawed installation method caused at my thread That red dribble. You can see the crimpping on the clamp that was the root cause of the problem in the first pictures where I show the ATF drip.

I'm not sure if this was the factory installation method or not, but if it is, then those of us with the ~30 year old cars are all probably due to start seeing this issue.

Srry for the thread revival but.... Mercedes w123 Maintenance: Its dribbling ATF!.. why and the (temporary) fix

Best fix
 

Cut out the leak with pipe cutter and install a 14mm hydraulic coupler. The part is $14. The beauty of this fix is that you can clamp the coupler super tight using the original clamp site and you wont have vibration issues as you would with this hose-clamp solution.