i have the same problem. it's also killing my gas mileage. until that f#@*ing abs light comes on, the brakes will engage slightly.
if you listen close you can hear it. nissan, in all it's infinite wisdom, decided it wasn't a "recallable" problem and decided to just do an upgrade. at nissan, parts and labor $400. the part is special order also, so chances are you aren't going to find it anywhere except nissan. good luck.