Sticker is slapped on wrong
Doesn't matter though dude, I've come across this question a few times and you simply just can't pay attention to the sticker. Although it's annoying that it's upside down, trust us in that the bottom fan intakes air and then the one on the back blows it out. Should be sucking hot air right off your CPU actually so it should help the entire system out a little which I think is generally the idea. Just adding another port for air to escape from the entire box.
Like I said though, don't worry about the sticker....unless you're really concerned then you could always cut a hole out the top of your case and put the PSU upside down so the sticker is the right way