It’s sounds like it’s just a mistake.
There isn’t anything in the rules that address how to correct this. Since it sounds like the disclosure was given timely and there was no real issue, the concern is documenting your file for auditors and examiners – when examiners see dates that differ from the signature date it can cause questions. I suggest a note to the file, either on a checklist if you maintain one or a memo, indicating the issue, why it occurred, when the disclosure was actually delivered and if you reminded the LO or your staff to verify the correct date before issuing. This note to the file will re-enforce when the disclosure was provided and prove that you recognized the error and have taken step to prevent it going forward.