I talked to humminbird about the issue and they recommended that I ease the unit coming out of the car when there is a great temp difference. You can wrap it in a towel or a jacket and place it on your kayak for a few minutes before unwrapping to acclimate. A fleece or neoprene bag would even be better.
Its hard for me to blame them. My waterproof camera and my slr lenses do the same thing. I just hope its a condensation problem and not shorted out.
The last occasion, it looked like it was raining in my ff
/bing