confusion

I scheduled an appointment to have my new car inspected. My mechanic approved of my choice of vehicle, which is a good sign. They set it up for inspection and said that they would look the car over thoroughly; they take a "holistic" approach, which works well, because they catch problems before they become big. So a few hours after I dropped the car off, the service manager called me and said that they were going to do the 30K mile scheduled maintenance. I told them to wait; he told me that they had to replace the spark plugs, which clearly had not been replaced at 30K miles (now the car has 34K). I called the dealer, because the dealer had told me earlier that the car HAD had the 30K service. The dealer said he would check with the service department there. Thirty minutes later the dealer called back. He said that they had done the service, but had FORGOTTEN to replace the spark plugs. This sounded sketchy to me. I called my mechanic and told them to go ahead. Better safe than sorry. The dealer just dropped a notch or two in my book. But car salesmen will tell you anything to get a sale, it appears.