Are Tablets Accelerometer different then Phone?
I don't know, but it would not surprise me if (some) tablets regarded landscape orientation as normal, and the accelerometer axes were oriented accordingly.
And if you're running an emulator, all bets are off ;-)
On a related note: in my bang-it-up-fast code, I used orientation values 8,9,6,3,2,1,4,7 arranged as per numeric keypad, but in retrospect, would be better just using degrees (or multiples of 45 or 90 degrees).