To repeat myself, this is a distinctly new behavior just in the last few months. I've had this car for 4 years and had the same tires for 2 years (they still have plenty of tread left) and I've driven the car the same way for all of that time and never had any issues. And these incidents occur on dry, even pavement.
Yaw rate is the rate of rotation about the vehicle's vertical axis. The stability control is activated when the EBCM determines that the desired yaw rate does not match the actual yaw rate as measured by the yaw rate sensor.
Have you had this yaw rate sensor replaced? AFAIK, it is a tiny module buried in the center console on the Gen1 and must be programmed using the Vehicle Yaw Sensor Learn procedure if replaced.
ESP ESC Stability Control Intervention Very Early on Holden Volt
EDIT: Similar symptoms, i.e. stability control engages on freeway ramp detailed in the above linked thread ended up being a 'ESC software' issue according to the OP on a Aussie Holden Volt...