AC4040BSI gain being reset to default of 1650 on it’s own

I have been struggling with calibration of this camera, and was finally making progress by lowering the gain from 1650 to 1500. However, while working on a target for 10 nights I noticed that half way thru the gain had been reset to the default of 1650. I have not determined what event did it, or what impact it will have on my final image. Under what conditions can this happen? Can I override it?

 

Readout mode was High Gain, exposure 0.15 sec.

 

Maxim V6.50
dlapi.dll ......................... 2.8.0.0
DLAPIWrapper.dll .................. 2.8.0.0
ASCOM.DLImaging.Camera.dll ........ 6.4.23.0
ASCOM.DLImaging.CameraExt.dll ..... 6.4.23.0
ASCOM.DLImaging.FilterWheel.dll ... 6.4.23.0
ftd2xx.dll ........................ 3.2.14.0
ftd3xx.dll ........................ 1.3.0.4
wpcap.dll ......................... Not Installed
packet.dll ........................ Not Installed

 

I have checking the gain before every session lately. It has not happened lately so I assume it is resolved. Thanks for your help.