All rotors will rust, even overnight if the humidify is high. Also some rotors will make noise until the rust it wore off. Unless rotors are "pulsing" when you put the brake on,(you feel vibration) they do not need to be replaced. I would take it to another place for second opinion. I can tell you horror stories of people who went to Big Name places and told it would cost $700 or $800 to replace everything. I was able to just replace the bad parts for less them $100.
NOTE: I think my point was missed. Brake place said rotors, pads calipers back drums, back shoes, back cylinders. BUT, vehicle only needed front pads and one rotor. My point is that customer was getting RIPPED off, with saying that unnecessary items needed to be replaced, when in fact nothing was wrong with them.