I understand your concern. You have done nothing wrong. There are some instances where the IRS does not receive copies of all your income forms as they should have, from the issuer. In that case, they can't really tell what forms are missing in order to verify your tax withheld. They just need to see your copies to tell what they're missing. It usually can take up to a year for them to be able to match the income you report to the various sources of that income so it's much faster and easier for you to just send them a copy of anything that showed tax withheld.
