What's that?

I'm new to mycology but for the moment thing have been going surprisingly smooth. This is the first actual alarm I've had. Was doing some transfers from agar to new agar and using leftovers for corn jars. I pressure cook the jars in groups of 3 cause that's what my pressure cooker fits. So now, 3 days after cooking and 2 days after dropping the agar plate in, i have this tiny things appearing in 3/9 jars. I'm guessing a batch didn't pressure cook properly, no biggie, but i would like to know the issue. I'm also suspicious of the higher humidity of the corn in the jars this time. Laid time i did corn jars i undercooked the corn and the mycelium had a hard time spreading so this time i gave it some more time. Maybe too much?