Front Differential leak?

No clue other than it's a Lexus part that Toyota would need to do extensive testing on (with how anal they are with some things). Even though many here (including me) have switched, they're probably not messing with the thing they know works in this configuration.

@fxntime hard to tell from the pic OP supplied but the washer is a pretty tight fit through the threads. Unless it was damaged prior to installation, I don't see how that would be the leak point.

 

There's two points of fail here: at the factory and at the dealer during the PDI. Toyota came out with a few TSBs admonishing dealers for doing hack job PDIs.

But that's what happens when you pay flat rate.