FBR q- grandmother lied about age

So I’m at the early stages of collecting all the documents for get on the FBR. My grandmother was born in Ireland and came to the USA in the 50s. I haven’t received her marriage certificate yet but we are now aware (after her death) that she lied about her age to my grandfather so that she could marry him. If the year on the marriage certificate doesn’t match the birth certificate do you think that I will have an issue? Her death certificate has the correct year.