Module getting out of calibration out of nowhere, anyone else?

I have been running the modules on my battery for a month, never had any problems apart big voltage fluctuations while charging.
The last time i touched the modules it was to flash all of them (32) with the latest code a week ago.
Today i got scared one module in the middle of the pack decided to show a voltage value 100mv less than it should. All cells are balanced to 10mv difference.
I look at the calibration multiplier to get the real voltage reading the value had to be increased to 2.26 instead of 2.2 or 2.1 that this and all the other modules have.
Am i the only one?