heya!
i play the flute 2! i really wouldn't worry, i have those days all the time, just keep practising and the beautiful tone will soon come back!
i don't know if you've got the trevor wye book? it's called trevor wye's practice books for the flute? there are five, and book one concentrates on tone, ever since i have had it, i've found my tone has become clearer and richer! it really is a must have!!!
by the way, an hour a day is really impressive!!! i'm in between grade 7 and 8, and i can't find time to do an hour!! i think maybe i should!
good luck with your audition!