iPhone accelerometer... LEFT?!

Hi there,
I have some problems when gaming on the iPhone, especially games that use the accelerometer.
For example, 'Cube Runner' (free on the App Store): I put the iPhone on a flat table, I launch the application and start the game: the ship goes left! [isn't it supposed to go straight!?]
Another example: 'Aqua Moto Racing' (free on the App Store): I repeat as above, and the water bike goes left...

So, what can I do?
If I go to a genius bar, they're going to fix it even if I have these problems only with non-Apple applications?

Thank you.

 

I tried with iHandy Level Free and it says 1.8° and the bubble is on the right. So I guess that my accelerometer is 1.8° skewed on the left...

Even with games calibration I have no results.
The problem is only with games, when I start the iPod mode I see the titles of the songs, not coverflow...

PS: I already tried to reset & restore as a new phone in itunes.

So what can I do? Do you think that they'll substitute it for me?