Hoping someone can ID a weird thing with a couple of my pumpkins so I can avoid a repeat.

I grew one Jack O'Lantern vine from seed which produced 2 pumpkins, both of which got this raised whitish stuff on them. Can't recall how sudden onset was, but It appeared on the tops/sides of both at about the same time after they turned orange.

Left photo was at harvest, right is after a long cure.

It didn't look like scarring, but as if something got spilled on them. Due to its odd trailing/spattering pattern I first thought it was bird poop and tried to scrape it off, only it didn't want to come off like a residue would. So I'm guessing it's some kind of damage from insects or fungus or something, but I've never seen anything like it.

I grew several more pumpkins of other varieties, some in close proximity to these, and none of them developed this.

In case this is a related clue, here's a photo of one of those pumpkins as it was growing - I remember noticing the stems had odd silvery trails beneath their surface (it wouldn't scratch off), almost like leaf miner-looking, except I've never seen that on a stem before. This doesn't seem to have had any negative impact on the health or appearance of the stem though.