Does it push back once per press of the brakes or repetidly? If it does it more than once does it get slower as the car slows down. How long ago after fitting the brakes did the problem start. And how long was your bedding in process, if you don't have warning lights first check the abs light is present(it is possible it's been removed and unless you look for it most people won't notice) I wouldn't bother checking the abs if the light is there and goes out as it should not until you've checked for warped discs. If the problem was from the moment you fitted them then check that the disks are seated on the hubs correctly. A piece of rust or crap will make the disks sit funny and give the same effect of being warped... Hope I've helped