I came across this info from
www.techauthority.com
2011LCOM1PDF
2011 Dodge Challenger Owner's Manual 1st Edition PDF ( English )
Manual Transmission
As follows,
Due to the high performance nature of your drivetrain, you may hear your transmission. This can be most noticeable when the vehicle is idling in NEUTRAL with the clutch engaged ( clutch pedal released ), but it may also be heard when driving at low engine RPM. Also, this may may be more noticeable when the transmission is warm. This is a normal condition and is not an indication of a problem with your clutch or transmission.
This pretty much sums up what I'm hearing.