The question I have is whether the traction was bad, and the rear wheels were actually locking up, or whether the ABS was releasing the rear breaks when the wheels were NOT locking up. up, or whether the ABS was releasing the rear breaks when the wheels were NOT locking up.
It was raining and slippery. No, I never felt any wheels lock up so I guess it did its job... sort of...
However, I had just replaced all the front brake hardware that day. Its possible that the new pads were not seated to the new rotors equally on the driver & passenger side yet. Sometimes this takes a few miles. What I'm getting at is that there could have been some funky imbalance in the whole braking system exacerbating the abs effect; and on wet slippery roads... I'm just speculating.