Well, it's not as clear-cut as YA books (or adult books), but I'd say these have hints of it:
The Lost Prince by Frances Hodgson Burnett (one of my favorites, though perhaps not a deliberate deception),
The Thief by Megan Whalen Turner (probably borderline YA, though),
perhaps The False Prince by Jennifer Nielsen (though it's not a deliberate deception there)
I suspect it's harder in middle grade because it's harder to 'lose' the trust of the reader without undermining the whole purpose of the middle grade novel?