while braking, if i go over a small pot hole or a bump, or uneven pavement, i think the abs engages. the brake pedal shakes. i dont think the rotors are warped, the doesnt shake while slowing down on high speeds or when i lightly press the brakes on high speeds.

 

Yes, it is the ABS engaging. Effecively your wheel hopped or slipped a bit making the onboard ABS sensor thinking the wheel is slipping. Thus it turns on the ABS.

Bottom line, it has low tolerance, but it is normal operation