Cary SLI-80: static when I touch the balance knob

I get buzzing and static at the lightest touch of my balance knob on SLI-80 -- this only happens when there is no source playing, as soon as play a source the static goes away and everything appears/plays and balance knob works as normal. I discovered this accidently tonight. Is this a sign that something is on the fritz inside the Cary, or should I just try and ignore it? What could this be?

Thanks,

Jason