Give it some lube next time might have damaged the seal when it first turned because there wasn't any lube allowing it to leak. Transmission might be low due to temperature outside since hydraulic fluid does expand and contract depending on temperature. Other thing is to clean the yoke surface so u have a smooth clean surface for the seal to mate with. Check the level of ur t-case. If it does pour out then that seal which I am pretty sure is very similar to the one on the tail shaft might be leaking. It may even be lower then the level due to temperature.
1992 Jeep Cherokee
1985 Chevy 4x4