1999 BMW 328 BMW Brake roughness

Brakes problem
1999 BMW 328 V6 Two Wheel Drive Manual 50000 miles

I have a 1999 BMW 328i Convertible 5 speed. It snowed a few days ago and the Antilock braking system and traction was engaging a lot for most of that day. After that, the car sat for a few days. Took it out today (dry day, no more snow) and noticed the brakes were "rough". I would get a "rippling" feeling and brakes did not seem to grab well. This feeling is not of a consistent frequency like a bump on rotor, but somewhat random pattern. What's going on here? Did the excessive use of the ABS cause some permanent problem? What is the cure? The brakes prior to this was crisp, sure, and stopped on a dime with excellent control. Now it seems to be greatly underperforming!