Popcorn spawn - Are these white spots of concern?

Four days ago I added some purchased oyster spawn to five jars containing popcorn or rye (after sterilizing of course). The next day I noticed these white spots on the kernels of only one jar. For reference, the pink oyster spawn in this jar was also added to a jar of rye, and there is no sign of these spots in that jar, so I believe the spawn itself was fine. Transfer was done in a still-air box, and this wasn’t even the last jar I did, so I’m not really sure if it is contam or not?

One thing that strikes me (and I’m not sure if you can see the detail in this pic), I have seen white spots like this on sweet corn, which I believe is also a fungus, but the popcorn kernels were boiled for 20 minutes, dried for a couple hours, then put in a pressure cooker for 90 minutes at 15psi, so I don’t know how any fungus would have remained in the jars?

Regardless, I was wondering if anyone had seen something like this before, and if the jar is likely a loss? The oyster spawn is actually growing growing, you can see one cluster starting right in the center, and it seems like it’s cleaning the kernels that it expands to? This is my first time trying to expand spawn so I thought I’d ask for opinions on this…

https://mander.xyz/pictrs/image/81a67626-7bfa-44f7-b119-5b168380eb30.jpeg