yes and no. some contamination will only become active after mycelium grows. but for the most part yes you would see comtam then. then again the cold helps to resist contamination giving time to the mycelium to consume it before it becomes anything.(germinate)
its a living organism, contams, are an issue, but made out to be bigger than they are. if you follow procedure and use good methods and feel confidant and listen to the little advice like "dont pass your hands over open containers" you will be fine. as ive become more experienced i have even let contaminated jars go on without any attention to come back and find pure white mycelium. they did contam in the end, but i did get some fruit. with mycology its all experiece you can learn a lot in a little time with mushrooms, and bouce right back, with weed its not the same, it doesnt grow in 6-8weeks and you cant just take a peice of that plant if you fuck up and continue on like you could a mushrooms.( essentially to make a clone of a mushroom(very simplistic, its not this easy!) all you need is a clean sterile piece of mycelium or fruit, and put that into a sterile substrate to regrow.)