When it bucked last night, I was in auto mode, in a parking lot and barely moving. When I tried to manually place it in 4lo this morning, I was in park. I guess I'll dig through the owner's manual to correct my understanding on how it is supposed to work.
As an aside, I had the fluid in both differentials changed approximately 3 weeks ago, and am 99% sure my mechanic used the right fluid (he's honest, and I told him EXACTLY which kind to use.
And thank you for your kind answers. I am new to 4 wheel drive, but am soaking up as much as I can about it. Spent the last few weeks boning up on Quadrasteer...