Mold from Fish Oil Fertilizer

Hello Everyone, I'm new to permaculture as well as gardening. I've started growing some plants from seed for our garden. I bought them from Baker Creek and they seem to be doing great. A few days ago I watered them with a fish oil fertilizer and noticed that the tops had molded over. I'm not sure if this is something I should be concerned about. Please let me know if you have any input or if there is more information needed to respond.

Thanks in advance for all responses.