Brake warping is when the brake rotors are no longer flat and usually is caused from heat from the brake pads along with the rotors getting too thin. The warping is usually not visable with the eye, a slight warp can cause brake chatter at highway speeds. The cure is to replace the rotors with new ones and normally the brake pads are replaced also.
I prefer to perform a visual inspection of my cars first before I attempt to drive at highway speeds.
1998 Mercedes E320, 200K Miles
2001 Acura 3.2TL, 178K Miles
1992 Chevy Astro, 205K Miles