I have a bay window in the master bedroom which consists of 5 panes. I also have georgian white bars. One of the panes has clusters of what looks like very tiny blisters/pinholes in it. I don't recall seeing these when they were originally installed. Very noticeable when the sun shines on the glass. What do you think it could be and how did they get there? I did ask a window fitter when he came to do a downstairs window and he said it could be from the factory. that the machinery caused it, but as I say it was a few years later that I noticed it. But of course I could have overlooked it.