Uplinker - as others have said the T/O CONFIG just checks that there is a plausible flap setting for takeoff (CONF1, 2 or 3). It does NOT xcheck the FMGC.
Quite disappointing that the warning doesn't check the flap setting. You'd think that it'd be an easy fix- sort of like the lack of a "fuel leak" alert in the FMS- which Boeing implemented ages ago.