It's quite possible that the car did not display the codes every time. Sometimes the speed sensor/abs harness area doesn't even throw codes. I had the same issue, only my ABS actually did fail while I was hitting the brakes, the light came on right after but went off after turning the car on and off. I used an OBDII reader and nothing. As a precaution, I bought new front wheel sensors and wiring harnesses. When I took the car to the dealer for install, I saw for myself that the PIWIS did not even have a code on it in any of the modules.

I replaced all the stuff anyways, have not had the code since. This was less than a month ago. My mechanic said there have been a large influx of these recently and my car has only 38k miles on it. Seems like they are going over time, especially on lowered cars.