Why does TurboTax show a different amount owed to me after I've already filed my taxes?

I opened TurboTax to see if I could change my State tax.  When I opened it, it asked if I wanted to update the program.  So I did.  Now my Federal Tax return is showing a different amount owed to us (we paid when I filed back in early March).  Why is that?  Should I file an amended tax return?