As we were cleaning out the brooder today I was handling all of the chicks like I normally do and I noticed all of them have very hard crops, about the size of a regular bouncy ball but not that solid. Should I worry? They are about 4ish maybe 5ish weeks old (hard to say the guy we bought them from said they were 2 weeks old but when I showed pictures here most folks agreed they were probably 4ish weeks old)