Tiny dots on substrate

Hey everyone my friend has Golden techer that's fully colonized on bulk substrate n they have this little yellow dots all over any one know
what they are should he be worried. My camera is an old one the pics are not

Not 100% but looks like metabolites

what was the bulk sub? could be the grain if grain was used, dont really look like Teacher's pin heads

Yeah pinheads would appear darker, orange/brownish.