I own a four year old house with dual-pane windows.  Last week when I was washing the windows I noticed that some moisture had gotten between the glass panels on a couple of the windows.  I thought it was from using the hose, but when I went inside to check the glass panels they were absolutely dry.  I also saw dry water stains on the sheet rock around the top and sides of the windows.  Obviously, this has been going on for some time.  Any ideas about where the moisture is coming in from?     T. Butler, Castro Valley