1998 W210 E300D.
Two days ago, I noticed some diesel on the garage floor. Cleaned it up and more appeared later that day. I suspected it was coming from the shut off valve so I wrapped a rag around it and the rag got pretty wet with diesel a few hours later. Moved the car to the driveway this morning and don't see any signs of diesel fuel leaking. I placed paper towels around the shut off valve and they're dry and no more drips on the ground. Fuel lines are clear, i.e. no air. And the car starts and shuts off normally without any problems. The weather was very cold the last few days so I wonder if that had anything to do with it, I am completely baffled.