iMore

Developers noticed the issue, and decided to try and get to the bottom of it...and as it turns out, it actually seems to be simply a problem with calibration, and not with the hardware itself! That is good news for the end user for a few reasons...it basically means that new calibration options can be added by Apple for people who are finding issues getting the "sweet spot" on their iPhone, AND there is no long term "problem" when it comes to gaming because developers were already aware of this and have been using a work around anyways when developing their games (or adjustment pre-existing games).

So basically...the problem comes from calibration, not an actual problem with the hardware. That should put some fears about an inferior accelerometer to rest. Here's a link to read about it.

How to work around accelerometer bias on the iPhone 5S ? Mobile Spatial Sensing