Thank you Smketter and mbrower for your suggestions. So if I understand you Smketter you do not have to change the rotors when you change the brake pads? My mechanic did not give me any reason for his suggesting I change the rotors, except that I have a Ford maintenance plan which will give me free brake pads but I would have to pay to replace the rotors, and I also think they will only give me OEM brake pads for free. I may have to shop around and really see if other mechanics think I need to change the rotors also.
P.S. My Ford maintenance plan, which I purchased when I bought the F-150, will only give me free brake pads when my pads are 4mm or less and currently my pads are at 30mm. I think I'm going to shop around for some of the more heavy duty brake pads and see if I really need to change the rotors.