water has got into the watch. everytime you wear it the heat of you arm makes it condensate. I suspect that you have also had a replacment battery fitted? the new seal is so good that it has trapped the water inside the watch. you need to take the back off the watch and let it dry out thoroughly before fitting the back plate back in place. you may want to consider getting a watch repairer to fit a new seal once it has dried out to make sure it is sealed properly.
jason, May 2011