I must admit, my thoughts went to a broken ABS ring.
In the past, when I first got hold of my 9-5 Aero's, and driving

, they used to briefly apply the rear brake when cornering, but after the first couple of times they seemed to get trained to interfere less.
Yaw angle stuff I have seen a lot on the NG 9-5's, but they seem to be ghost errors, never being of substance.
One day I was messing about with toe in, and did manage to get it so far out that I had the ESP light up & complain, so maybe a quick tracking check might be in order. If you don't have gauges or any favours to call in, then you can make surpriingly accurate measurements with some string, a rule and some chalk