Microsoft has rolled out a new update to the Windows Device Recovery Tool (WDRT). According to the update prompt, seen below, this latest update is mandatory, and includes updates to the HoloLens recovery.
For those unfamiliar, WDRT is a tool that allows Windows Phone and HoloLens users to easily restore their devices in case of an issue. Once this update is installed, you should expect WDRT to move from version 3.7.18601 to 3.8.19701. Other than the update to the HoloLens recovery, it there doesn't appear to be anything else new. You'll want to install the update anyway, however, due to its mandatory nature.