I posted this a while back, but no solution was found, so I'll try again...
At the rear of the MDX, a small amount of oil drips from the bolt that hangs at the center of the spare tire. Just enough oil for a drop the size of a dime. Doesn't happen all the time, but quite frequently.
Dealer said it was from lubricant used on the spare tire cable. They cleaned it off, but the leak is still there.