2002 Explorer Sport Rubbing Sound

My 2002 Explorer Sport 4L V6 with 35K miles last week started having a
"rubbing" sound, when I turn the steering wheel. It is not a loud
sound, and is probably not noticeable by the passenger. When I turn
the steering wheel lock-to-lock, it makes the sound two or three
times. It may be more detectable by feel by the driver than by sound.

I had the mechanic at my local shop test drive the Explorer while it
was in for an oil change. He heard the sound, but didn't know what it
was. He offered to check to see if there were any techical notices
about it from Ford, but he suggested I take it to a dealer to get it
checked.

Before I do that, does this sound like something anyone here has
experienced?

Thanks,

Greg