If you are feeling a lump in the throat/chest area that goes away over night you are probably just feeling a full crop. This is normal. Chickens fill their crop with food throughout the day, and then move it along the digestive process overnight. If there was a problem the birds crop would not empty on its own...or at least that's how I understand it. Are your birds otherwise acting normal? Active, eating and drinking well, alert? If so, then they are probably fine. Try doing a search for sour crop symptoms and see if your birds are exhibiting any of them....other than a lump. Hope that helps.