@tacomamold,
They have special tools you could purchase to detect if the mold is bad.
You also have solutions to mix the mold in and even lab tests.
I have black-mold, had to scrap it off, and apply anti-mold, then paint it
after it was dried. In fact to get rid of it the entire area needs to replaced.
I think you should be scared if it looks odd. The reality is that mold is everywhere, and if the area is damp enough it could grow. Untamed mold
could get big like coral-reefs. But again mold varies.