I don't think lead is typicaly used a a lubercant in diesel engine oil. It's unneeded in diesel, and typicaly baned for use in a motor fuel
. Lead was used as a octane enhancer in gasoline, and a a material to lube the valves on older gasoline engines. Diesel typicaly used sulfur compounds, or surfactants to lub the injector pumps.
However, lead is a common metal to find in bearings. If the level of lead in the oil was high, that could mean the bearing were wearing faster than normal.
That means checking for proper oil changes, proper oil pressure, and running the proper weight oil. It would also mean checking that you ahve it changed on a schedule to keep water
out of the oil if you don't run the engine often.
If you get only one report with an out of bounds result, I wouldn't be too worried. Somethings things happen. If it's a trend, you may want to start saving up for a rebuild