Gwen should get the erroneous missed payment corrected.
The section of the credit report indicates that Gwen made all her payments on time for the duration of the loan, except for one instance in 2008 where it shows an "X" for no payment made. If this is incorrect and she indeed made all her payments, she should reach out to the credit reporting agency or the lender to dispute the error and have it corrected, as it could negatively impact her credit score.