Am I under reacting?

I was braiding my 4 y.o. hair after the shower, and found this single white hair. Looks like new growth,as her hair is super long and this hair is very short. Her dad, immediately went to google it and says it's not good and we should get her checked. I looked it up, and says white hairs in children can be due to nutritional deficiency, stress, or genetics. My family has been prone to white hair at young ages, but I don't think this young. I feel like it's nothing, she a happy child, who is finding her own so she has some attitude. She eats pretty good, she's a toddler so she has her days.