I don't think there's anything to do.
If you do get another check (unlikely) ----
IRS Pub 559 --
"If the decedent accounted for income under the cash method, only those items actually or constructively received before death are included on the final return.
Income in Respect of a Decedent
All income the decedent would have received had death not occurred that was not properly includible on the final return, discussed earlier, is income in respect of a decedent.
How To Report
Income in respect of a decedent must be included in the income of one of the following.
- The decedent's estate, if the estate receives it.
- The beneficiary, if the right to income is passed directly to the beneficiary and the beneficiary receives it.
- Any person to whom the estate properly distributes the right to receive it."
