lube leak transfer case

[mtiniandrossi]

I just bought a used 2011 RX350. There are drips under the transfer case. 

The fluid was changed 3 weeks before I bot it, so I took it back there. They let me hang out with the mechanic.

He thought it was not cleaned off from the change, and I had purchased new fill plug gasket, so

I asked him to change the gasket just in case, which he did. No charge as the work was under warrantee.

I did notice a squirt of lube flew out when he removed the fill plug. I think they may have over filled it a bit?

One question I have; is there a vent of some kind or overflow tube on top of the transfer case that could be causing the leak?

Has anyone else had this leak at 100,000 miles? Was it a bad gasket? If so which one? There seems to be a few gaskets as far as I can tell from looking at pics online.

Thanks for any help.