I'm happy to let someone correct my thinking, but personally I'd consider that a low risk issue - if it's a one-off, we sent the disclosure as soon as we could, and it's not something that is likely to recur. Document and move on. On the other hand, if the process that produces the file is susceptible to error, I would consider updating procedure to ensure that the disclosures go out in 2 days instead of 3, to mitigate the risk of recurrence - or figure out how to fix the tech issue. And then document those steps.
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Be kind; everyone you meet is fighting a hard battle.
--all opinions are my own--