Here you go - I knew I had photos somewhere! In the first pic you can see that the Barnevelder (the black/brown pullet at the back) has a full crop (the lump in her throat/chest):
In this pic you can see her stretching her neck and opening her mouth to move the food down from her crop to her gizzard:
Here's another pic (taken on the same day) showing a Light Sussex pullet doing the same thing.
They are not showing any signs of distress - in fact they seem quite relaxed. Before and after these photos were taken they were just hanging out with their sisters, preening and dosing.
Just to clarify:
If they were showing any sign of respiratory distress, if their open beaks were accompanied by wheezing or gasping, and/or if they were showing any other signs of ill health I would take them to the vet to be checked out for gape worm. In older hens with fully developed combs, another sign that they are struggling to breathe can be dark/blue tips on their combs.
These pullets (and yours, Jacinta) seem relaxed and in good health, so I don't believe there is any need to worry.