Hmmm interesting....also interesting that lead dropped down SO significantly. Lead was very high on your first sample.
The only theory I have...and it might be 100% wrong...is that the sample was taken at the very END of the oil drain. That could be the reason why the heavy lead drained out and wasn't included in the sample, and the lighter metals were still more abundant at the end of the drain.
Or there actually is significant engine wear...but then I don't understand why lead would be so low.