96 K1500 Brake Issue

[tempfixit]

I recently replaced the steel brake line from the gas tank area to the rear axle splitter to the wheels (bled the air at both rear wheels only). Under normal city driving conditions and normal braking, perodically the brakes make the noise like they are in the anti locking mode of a hard braking situation. Neither the brake light or ABS lite comes on when this happens. Any advice greatly appreciated.

Thanks in advance,