Mine is still very faint - will be listening very closely from now on - a long shot, but would this be covered under warranty - still under Audi warranty 'til December
Very dangerous... if left unattended the wheel can start to flop around and damage your brakes etc. in the process. Worse case is driving on a motorway and the wheel comes off making you suddenly change lanes and that could be a recipe for disaster in traffic conditions. Just keep listening out for rubbing/grinding noise from the wheels every now and then - music off/quiet road and listen to any sounds that may give you concern. Otherwise its real easy to do a basic test.. you could always jack the car up/use axle stands to be safe.. place your hands on the wheel at the 9 o'clock poistion and 3 o'clock position, gently try rocking the wheel as if you were going to take it off.. if there is excess play in the wheel then this could be a sign of potential wheel bearing failure.