OK, so the rear end oil level is often below the bearing when sitting level. They get occasionally oiled when you turn or side hill, park on off camber, etc. Ball and roller bearings do not need a lot of oil. But they need a good residual film.
So I have to ask, did you use synthetic gear lube?
The reason I ask, is because many synthetics have a lower surface tension than dino oils. That is one reason they can go lower viscosity when cold like 5W w/o needing a ton of VII's. But, the downside to these lubes is they also have less ability to maintain capillary fill. They drain off quicker. There is a some residual film of course, but it may be thinner ...
Dino oils usually have a mix of constituents and these tend to up the surface tension and do a better job at capillary fill. So I usually use high quality dino oils for stuff that sits around a lot. Of course if it's wet because it's under the full line, there is no need. But for components that have "splash" lubrication, I think dino's are better for the long sitters