Gotta be a fluid/fluid flow problem. I think the spec for the fluid and filter change is something dumb like 50k. Went 140k in one of mine, and filter and fluid were surgically clean. That isn't to say you shouldn't service it, but I think 100k is the best interval if you do all highway like me.
Whatever you do, DO NOT buy a flush of any kind. That will kill your trans. A real service is dropping the pan and replacing the filter, and it's not much more expensive than some ripoff flush that runs someone else's dirty fluid through your trans, and kicks up everything in the pan and the filter and circulates it in your trans. DO NOT even think of trying to add fluid or access the sealed dipstick. Even slightly over or under filling it may ruin it, and unless you are prepared to read the ECU for the temperatures, you can't even check it. RESIST THESE TEMPTATIONS!