Maybe it's because of inexperience, but I find when I try to mix at a quiet level that the same thing always happens every time. I can avoid it for awhile, but eventually, I'll pull a track up until it sounds right, and then I'll pull up all the other tracks until they match that one. By the time I'm done, I have a mix with every track's trim slammed, and then I have to turn the master fader down. It sucks. So I mix at a level where the tracks sound right which is indeed around 85 dbSPL.
Now, I CHECK my mixes loud and soft, and have caught things doing both that I otherwise wouldn't have.