I am curious to know the answer as well, since I'm going to be pulling my transmission soon as part of a clutch replacement.
I might suggest checking the transaxle oil and draining/replacing. Curiously, draining/filling wasn't part of
the instructions I read for dropping the transmission, so I guess you don't need to drain the oil to remove the transmission. Either that, or they thought it was so obvious that it didn't need to be mentioned.
Here is a very good set of instructions for actually flushing your transmission, not just draining and refilling. Note that some of this will need to be done after you reinstall the transmission.