What is the round circle next to the "do not dispose in household waste" icon on my Moto Droid? There is a round indicator of some sort under the battery cover approx 3/16" of an inch in diameter.  It is located to the left of the "Do not dispose with household waste" icon (looks like a trash can with an X over it.  The indicator appears white with red "X"s; I believe it has been this way since the phone was new, but I can't be sure.
What does this indicate?


Edit:  Added picture
Perhaps it's a water damage sticker -- it might go more red if water gets on it, or something.