My ESP BAS light will come on for no reason, stay on for a few minutes, and go off any ideas?

 

I had the bas light come on once while cliimbing an extremely muddy hill in the rain, I lost my bld function and only had open diff operation front and rear. After restarting, I got my bld function back and was able to get over the hill.

What does BAS mean?

also any ideas why this happened? It only happeneded that once and has been fine ever since.

Did I do something to cause it?