I have a 99 Mountaineer, 130,000 miles, runs great. Every now and then, I notice a small leak under the vehicle, which seems to be transmission fluid, but the tranny fluid or oil never seem to be low when I check the levels. And it seems to be coming from where the tubes run into the bottom of the radiator. Anyone have any idea where this leak might be coming from?

The place that changes my oil says it's nothing to worry about, but they don't have to clean my garage floor.