If the error was on the part of the DMDC and its data you made a good faith effort to complete the verification and have a safe harbor. If the error was on the part of the bank, wrong name, spelling or SSAN error, you can't un-ring that bell. It is a date sensitive issue and you cannot go back and make necessary disclosures now which were not made but should have been. If you treated a borrower as not covered when they are, the loan has risks for noncompliance and you could face issues if challenged.
If that is the case I would tag that file as such and to a large degree help the borrower whenever possible on this credit.
You can't really pull a new credit report if you have no reason. Technically you could say you have an existing relationship and use that as a reason but when asked "why" and the answer is "to see if we screwed up" is not a good reason. You could check the DMDC database directly. I've not used it before as I'm not a lender so ensure there is no agreement as to allowed reasons for access. You don't want to make a situation worse.
My opinions are not necessarily my employers.
Rules and Regs minus Relationships equals Resentment and Rebellion. John Maxwell