My wife's 500Mhz Pismo PB had (still has) the same white blotches. My Pismo, which was purchased at the exact same time, did not have them. They didn't bother her, and so we never did anything about them. I noticed the resemblance as soon as the first 'white spot' pictures started appearing. Unlike some reports here, however, her blotches never altered in size. I'll try and take a few pics of them if people want, but as I said before, they look like all of the other reports.
This rules out the magnetic lock as a cause, and anything else that is present in the Albook but not in the Pismo.
The blotches didn't affect her screen longevity, either. My Pismo's screen started to develop the 'pink wash on wake' issue early this year (I eventually replaced it with the new 12in Albook) but her screen is still fine.
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