The last couple of days I have seen a few hens almost throwing up when eating their Mash in the mornings, it's like the mucous that comes out of their mouth when chickens have crop but I don't think it is crop. I have turned 2 hens now upside down now to see if it's crop but no more or this stuff comes out and it only seems to happen in the mornings when they are eating. It's happened to a 16 weeks old Wyandotte and a Lav Araucana (not sure of age). Neither of these 2 birds have any troubles eating, they don't jerk their necks around to dislodge anything, they don't isolate themselves from the flock and their is not significant bulge in the crop area.
With the weather being colder in winter it could be that they aren't getting enough food from foraging or possibly even water during the night while they're sleeping so when morning comes around they gorge until they are too full, either of food or water or both.
I should add this in my threads now, I'm from Australia so it's the middle of summer here, they have plenty of cool water all day but I don't put water in the roost at night.
