Older sub with worn serial number

[dpa94114]

I've always been fascinated by the older dial on the subs from the 60s.

I've just seen a gorgeous older sub - Gilt chapter ring dial, some wear and tear, but pretty reasonable for early 60s - but the serial number is not visible (perhaps with loupe). Caseback is replacement, but has regular service dates inscribed over the years.

Very good seller.

Should the lack of a readable serial number make me run?

Thanks for any insight/thoughts...