Why did my budgie push one of her eggs to the side of the nest box?

Today is the 19th day that she started incubating the first egg. She has 6 eggs. I went to check and 5 eggs were in the middle and one on the side. I have candled all of them yesterday and they all look fertile and a live. I didn't touch them. i just opened the nest box a little and used a flashlight. Idk. I could have made a mistake and not all of them are a live but i am pretty sure they are all fertile though and they don't smell and the eggs are very white, a sign of fertile eggs. I'm just confused as to why she is pushing that egg away after she has been incubating them for 2 weeks and never pushed an egg away at all through the incubation period. Should I candle this egg or just leave her a lone for now? Thx