this is quite normal, the fogging will clear as the air temperature rises. If you use the 'van in Cold weather you may notice this also happens first thing in the Morning, either when the Sun shines, on just one part of a Window, or when you put the heating on and the inside Temperature Rises Quickly. Rob has covered all the options, however I just leave it to sort itself out. About Ten Years ago I bought a Brand New Swift, first time out two of the Front Windows Misted Badly. Following some previous advice, I removed the Clear Bungs, the windows didn't clear any quicker and it took me Days to get them back in. It is certainly nothing to worry about.
Regards Eddie 1 From Nottingham.