Ok. First, mist colors evident in the lower molds are as a result of spores and or spore bearing growth. It is difficult, for instance, to tell penicillin mold from pan cyan from mycelium color alone, but wait until that penicilium begin to produce green spores and it's pretty disgustingly evident.
Second, you may find that the color of your substrate will often show through your layer of mushroom mycelium and tint it brown or yellow.
Third, staining through subtle damage may cause your mushroom mycelium to look green. Metabolites emanating from your mycelium..or simply age may tint the stuff a yellow brown. If your grow is still contained in jars or bags and it seems to be any color but iridescent white, just wait a few days. If it hasn't turned black or green or pink or Grey then you are likely ok.
If you have mycelium exposed to the air, in particular, possibly able to contaminate your other grows, remove it from the premises and keep a close, CLOSE eye on it. If you see any of the previously mentioned colors, bag it up and toss it.
Do not "sniff" it. Inhalation of spores from the lower fungi can be a health hazard. I have a friend who sought to recycle his jars. He dug out the offending mold on his patio and wound up with a serious respiratory illness. A number of years ago I encountered an outbreak of what I believe was aspergillis and wound up with pneumonia. Whole I cannot absolutely assert the mold was the cause..... it probably was.
It's one thing to be exposed to the vagaries of atmospheric "flora", it is quite another to cultivate hundreds of millions of spores from unknown and otherwise relatively rare molds and then expose oneself to them.