Considering "born" is an irregular verb that appears identical in all its three tenses:

is born

was born

has been born

I think 'San's mistake is pretty understandable (he's no native speaker, but then, neither am I).

"Your language does not conform to established standards: correct it immediately!"

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"The warrior who does not know his business is like a cat that does not know the way of ratting."
- Tsukuhara Bokuden