Maybe not the rear main, but could be the rear cover which is common. In this case it won't likely sling off the flywheel, but can still drain down the back of the engine. This is very difficult to see.
In any case, fixing the rear cover gasket is the same process as the rear main and should be done together anyway.
Yup I forgot about that, good point. Seal could be ok but the cover seal shot.
I have this point I would like to make as well. On these newer trucks with the metal gaskets with the rubber embedded compared to the older style all gasket type, seems to me like on the hybrid gaskets, once they go, the whole thing is shot. Older school gaskets seemed to be more localized with seal failing/leaking. IMHO.