never experienced that in any of 7 DC vehicles that i've had the opportunity to drive on more than one occasion (5 of them are company cars). 3 of them had/have antilock brakes. i would have this inspected sooner rather than later. also, since it's free and easy, i'd take a look at the level of brake fluid, maybe it's a little low. it could also be time to bleed the brake system and fill it all back up again. but still, i'd do it soon.