Also had a problem like that on my Mazda. Also had it checked by the experts, and was advised that all was fine. However, I then took it to a different place to check again. They did an "on board" skimming of the disk, and I could clearly saw were the disk was warp. Apparently one of the causes can be that after heavy braking (with the disk warm) it is cooled suddenly, which then cause the warping. (Like driving thru a pool of water.)
Anyway, I was also advised that after the skimming, not to put the old disk pads back, although they were brand new, but rather to put brand new one's on. Reason being that the disk "settle's" on the old deformed disks and will then do the same to the newly skimmed disks. Hope this helps.