Dumbledore shaves the truth every which way, depending on his audience. If he had to be *forced* by circumstances to even tell the boy about the Prophecy, he is certainly not going to pop outthe very next year with "And now that you know what a Horcrux is, I have to tell you that you *are* one!"

With that silly sidestep about Nagini he managed to introduce the concept that a Horcrux *could* be a living creature. It is a clumsy device and she's capable of better, but I think the series has gotten out of hand and behaving like a very big dog taking its owner for a run.