2001 Accord -- weird sound from right rear wheel
 

My Honda is making a strange noise, and I'm hoping someone can give me an
idea as to what it is. After starting the car and traveling in reverse, I
get a buzzing noise from the right rear wheel. It lasts about 10 seconds,
and it changes in pitch as I slow down. Once going forward, I don't hear
anything, and it never happens again until the car sits for a while (turned
off). This sound never occurs while going forward. This sound is
different, I think, from the ABS brakes testing themselves. That is usually
a quick "thunk" noise when backing up.

Here are my Honda specs:

2001 EX
37000 miles (just out of warranty....it figures).
ABS brakes


Anyone have any ideas? I haven't had a chance to pull the tire yet, but
probably will do so soon.

TIA