@kreeger and Thomas: The film had been frozen but it was thoroughly thawed (for days) by the time I used it. It was also not expired or not by much, a very recent batch of PX125.
I haven't had a chance to develop more of the this batch, but hopefully it won't show up again, since I have about 4 possible diagnoses right now! Who knows?
Thanks for your help folkes.
Humidity / condensation damage. Can still be damaged like this from long term storage, especially freezer storage.
So is it best not to put films in freezer?
Originally Posted by Poisson Du Jour
I had similar damages with two PanF+ 35mm rolls.
Film placed into the freezer is best done using methods to prevent "Freezer Burn". This is done using an airtight package (sheet films and 120 and 220 are packed that way) or an airtight cannister. The 35mm films made today are not packed in airtight cans.