My brake mechanic showed me the leak. He indicated I should have it repaired right away. Warranty? If not, is there a DIY on this topic. How long can I go driving with this condition? Newbie..

Thanks

 

Yes it needs fixed, probably not warranty, but can't hurt to ask.
To fix it you need to remove the hub, which will require a large, possibly special socket. I'm not sure what AAM axles need. Pull the bearing and slide the hub off, replace the seal and re-install. Torque bearing nut properly.