At what age white hairs in beard are considered as normal?

Hi... my age is 28... im having good healthy black hairs on my head... my beard hairs will also look healthy... suddenly before 1 month I got one white hair on my chin beard... following that another white hair also came on my right side chin... im feel very embarrassed by seeing this white beard hairs... I dont smoke or drink... I dont have any white hairs on my head.. pls tell me how to get rid from this problem... im not married yet...
At what age white hairs in beard are considered as normal?
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