Nope. They are fine. The air sac is probably actually a little bigger than you think if you are going by your last mark at lockdown. Day 19 is fine. My last hatch most of them pipped at 19, though none zipped until 20. Just remember after they pip it can take up to 24 hours (possibily more, but usually within) before they actually zip and push themselves out and it is a wild and stressful ride, so grab a coffee, or your preferred drink and sit back and relax...lol Congrats on the experience!
LOL. That's natural, though if they have just pipped, you most likely won't be watching much except little beaks peeking out to get some fresh air. Make sure you keep us posted on the progress and when they hatch. How many do you have in the bator and what kind?
