Modem/Router combo reset itself

Hello,

I have the CG3000D and today the modem/router combo reset itself.  It erased all previous settings including my wifi network I had set up.  Was there a firmware update that was pushed to this device and that is why all of my settings disappeared on their own?  I've reset what I can remember and all is working, but I'm still left questioning why this happened. 

Looking for answers,

-A Cox customer