Upon looking in a PDF file named 2017 Guide, Manual, & Workshop Manual.pdf (maybe I named it that? I don't remember), all I found was this:
When an ABS or parking brake system concern exists, the ABS module sends the brake (red) warning indicator request
message to the GWM over the HS-CAN2. The GWM sends the brake (red) warning indicator request message to the IPC over
the HS-CAN3 to illuminate the ABS warning indictor and to turn on the check brake system message center warning display
Elsewhere in the owner's manual section it states:
Message: Check Brake System
The brake system needs servicing. Stop the vehicle in a safe
place. Contact an authorized dealer.
I might hook up a scan tool and see what codes are stored, or if you have to wait till it happens again, have the scan tool ready to do so. I mean one capable of Ford-specific codes, not just OBD2. If you can get a DTC code, or even if you can't, you could look through the PDF attached below, a '14 workshop manual section on abs troubleshooting including a list of what the DTC codes mean.
Once that message comes on, does it clear by itself while driving, or need the vehicle stopped or turned off or some other pattern?