I didn't see anything out of the ordinary. just make sure it's full of oil and pay attention to the pinion to see if it's leaking. might have been just how the photo looked. doesn't hurt to check the oil every once in a while! even the transfer case too.
when was the last time the diff oil was changed? most just keep topped off and forget it. if you have never changed it, I would think about that along with the transfer case lube too just so you have that peace of mind.