Hello Mommysongbird,
If the eggs were cold, that might make a difference in the flotation. How old are the eggs? You could try cracking one of the oldest into a bowl to see if it is still good.
Our eggs we do not refrigerate, and our "sell by" date is 4 weeks unrefrigerated from the date layed. If we find a hidden nest, we test our eggs by placing the room temperature egg in cold water - if the egg does not float, it is good. Sometimes they will half-float, where part is touching the bottom of the bowl, and the other is pointing upwards. We still use them, and they are fine. If we are unsure, we crack I to a separate bowl before using.
Hope this is helpful!