I have a 97 F350, 5.8 auto. When I first start it and start driving, the ABS light will come on. But 9 out of 10 times, if I activate the left or right turn signal, it goes out. The other 1 time it will stay on, until I shut down. It might repeat later, it might stay off all day.
My passenger car is a 98 Volvo. It has an intermittent ABS light that my mechanic said was due to a sensor problem. I learned to drive before ABS was invented, so I would say "nothing to worry about." Your stopping distance may be longer on slippery pavement since humans can't modulate the brakes on and off as fast as ABS, but then I'm not a big fan of tailgating when the pavement is slick!
Also, I'm guessing it won't be long before another wheel's sensor detects the issue and tells the computer to brake as fast as possible.