I have a 2003 G35 sedan.  It is RWD only, so it has the SLIP function to
help guide it on slippery road.

I've noticed lately that when I'm driving on snow, for instance, and the
SLIP engages, it also making a sort of groaning or creaking sound.  I did
not notice this last year, my first winter with the car, but I suppose it's
possible that this sound got by me.

Is this sound normal?  If not what might be causing it, and is it a warning
sign for my car?

Thanks.

Chuck