Seem to be! I checked half a dozen brand new ones at random (all diesels) when if first happened to me and they all did it. Not at all sure why. I tried a Mercedes too and that did it to a lesser extent. Obviously, the ABS pump is capable of letting pressure go if it decides that's the best thig to do. When it does so, it's supposed to block off the outlet from the master cylinder to the locked wheel so that your foot doesn't go to the floor. I'm guesing that whay you're experiencing is some weird trait that's connected to that ability because they certainly don't seem to do it when you're driving the car!
Obviously, with something as safety-critical as brakes, PLEASE don't take my observations as gospel though! Get it checked out - by a "main stealer" if necessary, even just for your own peace of mind!