My car does all the time and I was told by the dealership (and I think others on here confirmed it) that this is the ABS doing some sort of test/check and that the sound is normal. It really bothered me for the first few months of ownership because I did not know what was causing it. But once I learned the reason for the sound it's not a big deal - I still notice it and it is a minor annoyance (no other car I've ever had with ABS did this) at least I know it's not something wrong with the car.Thanks to the folks here confirming I'm not crazy. I, too, have the same sticky brake caliper and/or pad loosening itself upon initial brake application. It usually happens right at the first application of brakes after being parked a little bit.