2015 honda pilot told need new brake pads and machine rotors at 18,000 miles

Most likely , the pads are fine , AS FAR AS THICKNESS GOES , however , for the rotors to be warped at 18,000 miles , the most likely scenario BESIDES improperly torqued lug nuts , is overheating due to driving habits/conditions ( either aggressive , or excessive stop and go traffic). They probably do not want to re-use the original brake pads IF it is heat damage , and I would recommend the same. See it a lot , at a dealership near D.C. metro area, common because of traffic. -- Honda is not the only one with this issue and the pilot is a heavy vehicle , that will cook the brakes if you're not careful.