Random part found after rice soak.

I dropped my iPhone4 in a small amount of water and very quickly picked it up, dried it off, powered down and tore it down. I left the major components (Logic board, speaker, dock connector, battery, front panel on frame) in a large container of rice for three days. I went to rebuild today and found a small rubber piece that appears to have come off something in the rice. It is approx. 1/4" in length, 2mm by 2mm square and is C shaped. My guess is its a bumper for something but I can't see any obvious place for it to go. Thank you for your help!

Update, the phone is back together and working great. The piece appears to be non-essential or to have come from nowhere. Here are a few pictures.