The original double hung window was installed approx. 1 year ago. With changes in temperature outside vs inside, we noticed that one of panes of the window had accumulated moisture between the insulated glass sheets... which demonstrated that the seal was broken.
We reported it and asked for a replacement... but was surprised that though the window itself was under warranty, there was a labour charge to replace it.
My understandings of warranties says that labour and materials should have been all under warranty.