I was driving to work this morning and notice a semi audible tone that only lasted for a brief second while accelerating and it happened only while passing the 2k rpm mark in each of the gears going up thru 4th and after that point road noise and engine noise made it too hard to hear...It almost sounded like when you run your finger around the rim of a crystal glass...Like I said it only lasted for a brief second while going over the 2k rpm mark and was only noticable if you were accelerating moderately and paying attention...I know it may sound very strange and I promise I'm not making it up or crazy. Any Ideas to what may be causing this? This is the second time I've heard it. The first time I disregaurded it because I thought I was just hearing things