The CF card door on my D60 sticks. It is nearly impossible to slide open the door to extract the card. I am unable to find the wear issue that is creating the problem. I have resorted to leaving the card in place and connecting the camera to the computer to up load the photos.
Pressing on the door to slide it out and open is where the problem seems to be.
If you mean the SD card door on the 60D - wipe your fingers across your forehead or nose (assuming no makeup, of course), use that oil to lubricated the sides of the door.
disclaimer - I have no idea if this will damage the plastic if used long term, it's simply a solution I applied based upon somebody else' tip for lens hood lubrication, and it's worked for me for 6 months or so.