We have taken utmost care for handling these parts during and after processing the parts at our end. we have used light cotton gloves to handle the parts during processing to prevent the sweat/finger oil attacking the surface. we suspect the finger prints and oil marks are caused due to inadequate material handling. Not handling the parts with light cotton gloves can cause the sweat/oil/finger print impression on the surface. The mark shown in the second photograph is discoloration due to baking  as the part was placed on a cardboard sheet with this surface touching the sheet as there is no alternative to hold the parts during baking.