Is this is a "white lie" or should I be concerned?

There is this man that I've been talking to. We met online and we're considering meeting in person. Our conversations seem to go well but sometimes I have some doubts about him. I'm suspecting that he has been lying to me.

One month ago, he told me he had a nephew. Today, I asked him if he just had a nephew and he told me he has no nephews. Instead, he said he has two nieces.

Is this a "innocent" lie or a red flag?

If it helps, I can give more details.

Is this is a "white lie" or should I be concerned?
Post Opinion