Why was my white balance so erratic?

[teridash]

I've recently returned from a trip to Alaska where I photographed Coastal brown bears in Lake Clark and all manner of animals floating in the waters around Kenai Fjords National Park.  I always use auto white balance, and I have never had any issues with the wb being correct or easily corrected in LR in the past.  This time there were some issues!  Such as when I photographed the bears on the beach the wb was pretty much the same from image to image but when I was photographing the bears in the tall grass... there were some groups of images where the wb changed from warm to cool even though the settings remained the same and the time between shots was at most a minute or two.

And on the water, sometimes the water would be blue, blue green, green and almost grey.  I'm not sure if something was wrong with my A1 and 300mm or if it was something else like changes in sunlight, how the light was hitting the waves, when it was raining, or if it didn't like trying to figure out what to do with a brown bear surrounded by lots of green grass!  Had no issues other than those two instances.

Any ideas? Thanks