PET 2001-32 but with White screen

I just purchased a (perfectly mint!) PET 2001-32, but it has the white screen. I thought the white screens were early PETs, but I didn't think the 32K units were out at that time.

Were the 32K units available from the beginning perhaps? Or how'd I wind up with a white phosphor 32K 2001?

Thanks!
Dave