This happened to me too - when you go through a car wash the water cools off the radiator so the fan dosen't run. When the fan is running the steam is pulled into the engine compartment.

 

The steam most often can be linked to simple water on the radiator or AC condenser. The mondern cars in the in the winter will not always run the fan to circulate air over them and thus draw in the steam to the engine bay.

I have had this happen on my most recent cars.

If there is a sweet coolant smell then I would be worried. This also would possibly leave a coolant drip.

Remember that the coolant is under pressure once heated. If it were a real problem you would see it more pronounced.

I recently had to replace the radiator on my Jeep due to a bad seal. It did not stop the car, but there was steam and a very significant smell with it.

In your case I would so the 'smell test'.

 

Ahh, that would explain it. Thanks for the info!