Overhaul? Lead flakes in oil - interpretation please

I have a 1972 Volkswagon with a Volkswagon engine and it runs beautifully.
The engine is "original" and the speedo shows 280,000 miles (total time 2800
hours times 100 miles per hour). The engine had a thorough top overhaul
quite a few years ago, maybe around 150,000 miles (new pistons etc) and has
no problems with compression, oil consumption, vibration or indeed anything
at all. It is well looked after and has won many quarter mile drag races, at
least one a week!

Now the but.....

At its last annual (Christmas) some metal particles were found in the oil
filter.

Any advice / comments greatly appreciated.

"Believe it or not?"

;)

Peter