I know someone had this problem, but I can't find it.
Yesterday, riding in the rain, I noticed an ABS warning (red triangle). The ABS whizzy pump was fine, and the brakes were great and still had power assist.
Starting up, the light would flash. Normally it will go out when you roll. But, instead, it gave an error. This makes me think it is a wheel sensor. Today, after sitting overnight, it is fine again. I'm going to check the wiring, sensors, connections, etc., but if someone has run into this, chime in!