That's exacly what happened to me at 90k km (56k miles). It slipped, quite badly, while flooring it in any gear (in the torque zone), but some 3k kilometres later, it stopped. The car has now 99k km and no signs of chutch weakness at all.
I found it weird, as I drive 90% on B-roads, at 80 km/h - 50 mph (monthy average of 3,4 l/100km - 83 mpg now!!!), which causes next to no wear on the clutch.
Regarding driving a modern Diesel around town, it really is impressive what quoted mpg can do. Worse still, many people only buys a diesel "because diesels are more economical, end of story". Most of them never drove a small petrol around town, and realized how smooth and economical they are. Even so, EGR problems can also occur while driving on the open road, as it is my case...