I got it back today. The service ticket said "Clean Sensor, General Check and Clean, Adjust AF operation". I took it out of the box, set my 35mm prime to F22, pointed it at the sky, and the resulting picture had dust and an oil spot.
I wet cleaned the sensor, repeated the test, and the shot looked clean. I took about 50 pictures around the house and then took an F22 flash shot at a white wall. A new oil spot appeared. Sigh...
My guess is they totally ignored my letter that asked them to clean the excess oil from the mirror box. I even called them 3 times while the camera was in the shop and instructed them to clean the excess oil out of the mirror box. It obviously fell on deaf ears. I will have to keep wet cleaning my sensor.
I wish I kept my D90.