Federal Refund Changed Went from $6,435 to $8,679 After Submitted and Refund Received

Hi,

Strange, but good thing.  2 weeks ago I e-filed my federal return and received a refund of $6,435.  However, today I logged into TurboTax to print my state tax forms to mail and my refund went up from $6,435 to $8,679.  Good problem...right?  Why did this happen?  Turbo Tax did a software update when I logged in.  Did something change?  Do I need to do anything to get my extra refund - amend my form?  Nothing has changed for me tax wise since I initially filed.  This was all done and filed.  Why did Turbo Tax recalculate my refund after zero changes by me?  Just logged in and nothing else.

Thanks.

Jeff