When I candled at day 7, there were some eggs that didn't even look like they had an air sac. I assume this means they are bad? Also, I had one that was bubbling-that really doesn't seem good. Is is ok to candle again in a few days and just leave the good ones alone? I marked the ones that were good with faces. I marked the ones I was prtty sure were bad with and I left some blank if I wasn't very sure.