E-mail icon puzzlement (a.k.a. Nav bar oddities except with the E-mail icons) :p

The icon usage when looking at read and unread site e-mail messages (or PMs) seems kind of backwards to how you would think they would be. New unread messages are showing an opened envelope icon, while the ones that are already read are showing a sealed envelope icon. It seems to me that the unread ones would be the ones with the closed letter look, while the opened ones would look like the opened letter icon.