Nightmares

Andy has been waking up about once a week - screaming for mommy or daddy.  Usually, he falls quickly back to sleep after we reach him and doesn't remember why he was screaming in the first place.  The other day, the following conversation took place while we were playing with his cars/ferry boat:

Andy:  Mom, remember when we drove on the water?
Me:  You mean when we were riding in the inner-tube on the water behind the Sea Doo?
Andy:  No, when we drove the car on the water?
Me:  You mean when we drove our car on the ferry boat up to Whidbey?
Andy:  No, when you drove your car INTO the water?
Me:  No, Andy, did you have a dream about this last night?
Andy:  Yes
Me:  Were you scared?
Andy:  No, mom, I was brave (at this point, my heart aches).  And my head was still above water.  I could still breath.
Me:  Oh buddy, did we climb out of the car after we went in the water?
Andy:  No, mom.  I was buckled in my car seat.  How do people get out of their cars when they drive into the water?
Me:  Well, I would have used my mommy powers to get us out safely.
Andy:  No, I mean, how do cars get out of the water once they drive in the water?
Me:  There are special machines that have to lift cars out of the water.
Andy:  What is the name of the machine?
Me:  I'm not sure
Andy:  Is it called the car-picker-out-of-the-water machine?
Me:  Probably close to that.
Andy:  Cool, I am going to play with me cars.