Brake truoble on Hyundai Sante Fe

I have a 2002 Hyundai that is developing a vibration while braking. The first time this happened I took the vehical into the dealership and they said the rotors needed to be to be cut. That was done and about 5000 miles later the vibration cam back. At this point I took them off my self and had them cut at a locale auto parts store. The vibration is back again after another 5000 miles and I had them cut once again and the vibration went away again. So my question is, Is this normal? Is there anything that might cause they rotors to were unevenly so fast? I had also had the alignment check and they said that it was good and needed no adjustment.