I've had a similar experience with mine. Converter drained back and the fill tube O-ring leaked it all out. Topped it up and so far so good but I'm sure it shortened it's life up by 50,000 miles.

If it feels alright and the oil doesn't appear burnt, it likely didn't hurt itself. For peace of mind you could drop the pan and see what is in the bottom for trash. If the trans has some time on it, it will have some fine clutch friction material laying on the bottom anyway but if the residue is excessive or has pieces of material in it chances are she's scorched.

Heat isn't from the headers?

Good luck.

Kevin