I think it's a valid concern to have, but I wouldn't worry too much about it. Also, if the lease is through Ford, you can just turn it in how it is. As long as it still looks good, they usually won't care.
Also, I've leased a couple of cars in my past, and what I usually do is just sell them outright before the lease is up. I can usually sell them for more than the lease payoff, and Ford would rather have money than a used car, anyway.