Yes, but in the Ryans case, it involved the candidate himself (Ryan). Here, Romney was only a witness. Unless he lied under oath on something that could easily be proven untruth, the link is not that strong.
Plus, one has to wonder why the wife wouldn't have gone after this before now. If you "know" you've been cheated out of millions because some guy perjured himself, do you wait for years on the off chance he might run for President, then wait until the last week of October to make your move, or do you immediately file suit to get your money?