Serial Number for custom made MacBook Air's

Do CTO (Configured to Order) MacBook Air's come with the serial number laser etched on the bottom side?

Example: http://d3nevzfk7ii3be.cloudfront.net/igi/4Wx4yCNti2TFPvdl.large

Great. Thanks!

Reason I asked, it cause I've heard that if at the Genius Bar they replace the bottom shell of your computer, it will be without the serial number! I figured since its a build to order unit, if that rule applied.