Thanks for the input....
The theory about groove in the transmission certainly sounds logical to me. If this is the case, I guess there's not much I can do about it--except make sure to have my fluids changed frequently and to vary my speeds... right? Is it going to get worse over time?

I'm still wondering, however-- it doesn't do it often (or at least, I don't feel it often), and only once the first time I slow down/speed up after it warms up. Then it usually won't do it again in the same trip (which is why I've had a hard time showing the techs the problem).

And is it just coincidence that it seems to only happens when it's foggy/high humidity?

Or do these conditions make the groove in the runny surfaces of the tranny more noticable?

--Amy