Your first mistake was taking it to a dealer. I have never had service at a dealer where I wasn't over-charged, or where they tried to sell me something I didn't need.
The rust is normal. That being said, rotors aren't meant to last forever. Every time you apply the brakes a microscopic amount of metal is shaved off of the rotors. Rotors can become too thin to be safe.
Also, rotors can become warped if your wheels are torqued too tightly.
If I were you I would have the rotors replaced the next time you get new pads. Aftermarket parts dealers sell rotors for a lot less than the dealer.
The rust is normal. That being said, rotors aren't meant to last forever. Every time you apply the brakes a microscopic amount of metal is shaved off of the rotors. Rotors can become too thin to be safe.
Also, rotors can become warped if your wheels are torqued too tightly.
If I were you I would have the rotors replaced the next time you get new pads. Aftermarket parts dealers sell rotors for a lot less than the dealer.