This morning, Nvidia announced a voluntary recall on all Nvidia Shield tablets purchased between July 1, 2014 and July 1, 2015. Apparently there is a major battery overheating issue that they feel is sever enough to pose as a fire threat.
Again, this recall is voluntary, so you can decide to take your chance to keep using you Shield Tablet. But if your concerned, all the details of the recall can be found on the official Nvidia press release.
Also, there is a form to fill out in order to register for a replacement tablet, at no cost to you. Reading the form will explain in greater detail that the battery category has two potential options, B01 and Y01. It's the Y01 battery that should have you concerned. If you have a B01 battery, you have nothing to worry about.
Recall registration form can be found here. Start by downloading the most recent system updates and them walk through the steps on that page.
Did you have a Y01 battery Shield Tablet? Of course this comes as a surprise to us all. Who's bummed out? Are you going to take your chances and keep your shield anyway?