Audio hardware failure during the first 7 days of usage on a '13 Macbook Air?

A strange noise started to interfer with sound played by iTunes while I had connected an external speaker through the headphone jack, I stopped the music and noise was stil there, so I unplugged the external speaker and the noise started coming from the internal speakers, after 40 seconds, it stopped, and my sound was disabled, does anyone know what happened?

I've already rebooted and ran into diagnostic mode and told me that there may be an audio hardware problem, but it puzzles me how is it failing with so little use.