Denon 1602 whine at startup

lancer

I have a Denon 1602 avr reciever that has a whine that is heard through the speakers at startup. The pitch changes with the volume control adjustment. It goes away after about 3 minutes. No big deal just wondering what may cause this. Volume control is motorize

Denon 1602
Rt 7 Main
Center CS 30
Rt3 Surrounds
Velodyne 10" Sub
Samsung HD-931 DVD
Samsung Tantus 27" HDTV