If there was a mistake the college found on your financial aid forms…they could have changed the award. It’s very possible that they sent something to the student. This could happen at any time.
Or it might be a mistake NOW. Contact them by phone on Monday. And ask to speak to the financial aid officer who handles your son’s account.
Mistakes do happen…on either end.
You say these aren’t real numbers. If the amount is $2000 for the year, did your son already take the student Direct Loan? If not, that could cover this.