I noticed oil on the left side of my differential cover that has migrated out to the axle.
I've done some searching on this site and see quite a few pinion seal problems.
I'll be bringing it back to the dealership next week and would like to be prepared for any possible BS. Sorry, but I've had some bad experiences with dealerships when they are faced with warranty work.
Here's a photo.

 

Mine is about the same. If it ain't dripping, it ain't leaking, at least that's what Uncle Henry says.