I've just realized, for the nth time, that after someone says
...I'm past it
the interlocutor replies
You are?
I hope I'm right in saying that this is, strictly speaking, wrong, as the question should have verb and subject reversed:
Are you?
However I notice that in many spoken contexts the former is used.
My question is, given the two forms are exactly the same length, and take roughly the same time to be pronounced, why is the latter used at all? I mean, isn't having this two forms just redundant (beside the latter being wrong)?
From a non-native english speaker who's been living in UK for barely a year, I'm still far from being able to make any hypothesis on the reason why the You are? might have found it's place in the spoken language against the same-lengh, correct form Are you?.