As far as I understand it, the ABS Tone ring is a common issue, as I just experienced some issues with the front passenger side. The "internet" is flooded with questions about ABS lights coming on and off, ABS kicking in during normal conditions, etc.
My symptoms were as follows:
"Service 4WD System" HUD message
"Service Brake System" HUD message
ABS indicator intermittently illuminated
Intermittent ABS on non slippery road.
It sounds like the original part was made from mostly plastic, and will eventually break. The new replacement parts are made from mostly aluminum. The replacement part is cheap, but if you're having it replaced by a mechanic it'll run you ~$200 or more in labor.