Oh, how disappointing. But they don´t look like they´ve been dead for long. Do you think you had the days right? Could they have been due around now, and the chickens kicked them out and they cold cold and died now? They look like they died just days before they were due to hatch, and the darker one, so close. I don´t think it had anything to do with her coming off her nest for an hour. Gosling mortality is quite high even under the goose. Very disappointing. But at least you know they´re a fertile pair, and next time you could pop a number of eggs in the incubator, and leave a number of eggs with her to increase your chances. Well done on all your efforts. You didn´t deserve to lose them, for sure.