ABS light & Brakes

I bought a 2002 cavalier recently and the ABS light was on Took it to my mechanic checked for codes none were stored. when I start to drive it there's a rubbing sound from the rear brakes and they will lock up when I tap the brakes after it is driven for awhile they are fine. could it be that I'll need to replace the brake shoes? or is this a normal thing for cavaliers?