Yeah, I kept thinking 'what's that noise' 
heh glad its not just me that does that
- I think I was a tad concerned cause I know for the past few days theres been odd sounds coming from the direction of the PC and I need to open up the case and check the fans out, because something is playing up.
The background noise on the game sounded remarkably similar to the sound that my graphics card fan made once before just before it gave up the ghost - hence my concern.