Received Form 3531

When I filed my 2021 federal return with Turbotax, I forgot that I made estimated tax payments during 2021.  After I filed, the IRS contacted me and asked me to send in the first two pages of my form 1040 showing the estimated tax payments I made.  I also sent a statement from the IRS website proving the estimated tax payments were made.

 

Today I received Form 3531 along with the two pages of 1040 and the statement I sent to the IRS in April.  Box 1 on form 3531 is checked indicating  I need to sign my tax return. It's true that I didn't sign the revised 1040 I sent the IRS

 

Do I sign the 1040 they sent back to me?  There are red stamps on form1040 showing when the IRS received and then sent the form back to me.   Or do I prepare a new 1040 and sign that?

 

Thanks!