Transmission Tempature Light Came on.

I have never seen a Transmission tempature light, let alone have one come one.
I have a 2000 Dodge Durango with 78,050 miles,
it has a V8 dodge magnum engine.
Now it happened yesterday on the way home from work, while it was still raging hot out side, plus we were running the air conditioner. Pulled over right away to start checking fluid levels. Which all seem to be perfect. Nothing is too low or too high and all the fluids look pretty fresh. Although I am coming up on an oil change. So really, does anyone have a clue as to what could have made this light come on. After about 20 minutes of staring at the engine dumb founded with all the fluid levels fine. I got back in and drove home, and to work today without a single hitch. Plus no light. Any clues?