Hello and welcome to Just answer.com, Super mechanic here. About your vehicle.
There are several areas of the ABS system that will cause the light to come on.
Do you know what trouble code(s) are stored?
You will want to have the code(s) read to know what area may have caused this.
There has been a service bulletin for that type of concern. Here is what it states.
Bulletin No.: 03-05-25-007D
Date: May 01, 2009
Subject: Antilock Brake (ABS) Activation At Low Speeds (Clean Wheel Speed Sensor Mounting Surface)
Some customers may comment on ABS activation at low speeds, usually below 8 km/h (5 mph). Upon investigation, the technician will find no DTCs set.
The cause of this condition may be an increased air gap between the wheel speed sensor and the hub reluctor ring due to rust and debris built up on the sensor mounting surface.
Measure AC voltage and clean the wheel speed sensor mounting surfaces.