Vibration during braking

Hi - I just bought a 2004 with 30,000 miles on it and something doesn't feel right. When I go to brake, there is a vibration. I know the car has ABS and Traction control, but is THIS normal??? My previous vehicle was a 1998 Venture that had ABS (don't think it had traction control though) and it never did this. Can anyone else clarify what this might be? Also, before I bought mine, I test drove other 2004's and they didn't act like that.

THANKS!

Probably warped rotors, fairly common.