I did my double decoction last night and my plan was to collect my wort and boil it tonight once the little one goes to bed. I just stuck it in my kitchen in the brew kettle with the lid on it. Since I'm going to be boiling it again tonight anyways I shouldn't have to be too anal about sanitation right? No sense trying to make the lid air tight is what I mean..
I wouldn't really be worried about the bugs in the air but rather the nasties and lacto bugs in the mash...you will most likely be fine, but heating up the runnings to 180 or better yet 200 before letting it sit would clean it up nice prior to letting it sit.