Looks like I'm having the same problem.. Just drove cross country about 7 weeks ago and the Check Transmission light started blinking in Iowa after I dropped in a quart of oil. Had a local mechanic check the codes and there was nothing mentioned for the Transmission so he reset them and I drove another 1500 miles with no reoccurence.
But then a couple of weeks ago, the damn light started blinking again.. Reset the computer and it stopped blinking until last weekend. So now I'm starting to get a bit worried.
I've only put 15K on the vehicle since I bought it 3 years ago, and had ALL the fluids replaced 2 summers ago, including tranny and differentials. So I have a hard time believing that I'm running low since I'm not seeing any leaks.
As I recall, it's a major hassle to replace the tranny fluid, let alone replace the filter, but might have to do it.
Diogenes