A bit of proud and a sigh. She will probably have to study a bit more for the APs, but it probably will not be much. My son will do the same, get the extra then say "Oh I didn't think I filled out that part".
Its the I didn't even study or I don't know what the grade is or how well I did that gets me.
At the end of the year as my ds school it seems they give several extra credit opportunities, even in the AP classes. He snubs his nose at it. I tell him don't be so smug.
I'm not really in the camp of someone must fail. That bit of extra credit might give someone the opportunity just push them over 70 or 80% and mean the world to them and their parents.