The only thing I can think of is that it rained all night last night, so maybe it washed the poop away or something. I don't know. They haven't started laying eggs yet, so that's a good thing. They are about 20 weeks old. I hope they start laying soon, but not for another 2 weeks, apparently. I'm gonna be sad if I can't eat the first egg
They might not be laying because they have worms. You should probably also dust them for mites and lice, even if you can't see any. Tractor Suppy also has the poultry dust.