Tax Return - IRS notice

I filed my return as completed in TT (electronically).  I received a tax due notice for $403.  I went back to TT to review my filing but now the return shows $403 more in tax than what TT filed on my behalf.  Can someone explain why I was not notified of a change in the TT calculation.  I now paid interest on the late payment.

 

Peter Connolly