One of the byproducts of converting gasoline to energy is water/steam. If the air has moisture in it, that also comes out as water/steam. And if it puddles in your exhaust system will form acids strong enough to corrode metals.
So, good catch, OP
agreed, i was told many years ago that for every gallon of gas burnt an engine produces a pint of water. it only shows when the motor's cold by water dripping from the tailpipes.