Is is normal for brakes to lock if braking too hard while wearing in new brake pads. 2000 Holden Frontera UES V6

3 days ago I had my brake pads,rotors,calipers and disc replaced. The mechanic told me to take it easy on the brakes while they are in wearing stage. Today I was going about 40km and Im not sure if i hit the brakes too hard but as I went to brake and slow down the pedal would not push down and the brakes locked. Once stopped they were no longer locked and i continued to drive home and take caution with braking and nothing happened. Did I most likely brake too hard or does it sound like there’s still a problem with my brakes. Also my ABS light is always on

Make: Holden

Model: Frontera UES

Year: 2000

KMS: 210000

Engine: V6