The theory is, once they firm up in the direction they are in, they should stay that way. The air bubble gets stuck at the top and if you turn it over, the developing baby wont make it.
However, there have been a few people who have done tests where they turned the eggs this way and that and in their experiece, the hatch rate didn't really decline. I wonder how many eggs get moved around in nature by bugs, small animals, etc...you'd think Mother Nature would be prepared for this kind of thing. 
If your mother found them as soon as they were laid, they're probably just fine. (You may want to put a dot on them so that you'll know which way is "up" if for any reason you need to move them again.) Either way, I would absolutely let them incubate and see what happens. You'll probably be pleasantly surprised. 