I wouldn't worry about it now. Just leave them closed up tight. The carton works out well because they pop the top off like they are in an egg cup. I don't think I've had an upside down quail. Or if I did, I just thought it was a late quitter.
I always put the rubbermaid shelf liner down under the cartons too. It gives good traction for the chicks after they hatch and it helps to catch the hatch debris. I suppose it will give you some traction to stop the eggs from rolling a little. Originally I would throw them away, but it is a little pricey unless you can find it at the dollar store. But I've discovered it washes really well. Just throw them in your washer with a towel, they can even go in the dryer. I've been using the same ones continuously for a year now.
