best thing to do is to bring it back to Swatch Group in Wisma Goldhill as suggested by besview. I send all my Omegas there, better safe than sorry. Normally, if there is water vapor inside the glass, it could have gotten in when it was unscrewed to adjust time or date and your wife may have forgotten to screw it back tightly. Alternatively, there are other watch repair shops such as Watches of Switzerland. I haven't tried them before though...