On a '91 M5 80K miles....temperatures below ~40 degrees F cause the strangest sound-- immediately upon releasing the clutch after shifting into 2nd gear (during gradual acceleration) there is an audible 'click' (almost a 'clunk' but higher pitched) 'click' can also be FELT very slightly in the fingertips if holding shift knob... but ONLY in 2nd gear...and ONLY when cold--- the 'click' goes away after about 10 minutes of driving (once oil temperature is at 165 degrees or higher).......there are no other symptoms--the car does not pop out of 2nd gear; the synchros working fine apparently.... Any idea what causes this and what's the remedy? Thanks, Damian.