I liked the bright cheery feel of this image, although I do wonder if you could possibly have brightened it a little bit. It may have made the whites a bit whiter and the colours would have popped a bit more. Not a biggy and I know how hard it is to get it right!
I think the centered composition is quite fine, but I wonder also if perhaps a slight change would have pushed your score over the 6. Possibly moving the flower to either the left or the right may have helped a bit.
Nice shot. The out of focus petal in the bottom center of frame is somewhat distracting. I'd think I'd like to see the flower sitting a bit more to the right.