Roof leaks happen all the time. Most of the time, home owners get the roof leak repaired and think that everything will then dry out and be fine.
This usually isn't the case. You really need to have SERVPRO come out and read the moisture levels with state of the art equipment. If left unchecked many times moisture will cause mold to grow on the insulation and walls. This was the case with the picture your seeing. The owners had their roof leak repaired 3 weeks prior and then as time went by they saw mold growing. By the time it can be seen on the ceiling it may have been spreading and growing for weeks.
You want piece of mind that you are living in a safe environment.
Give SERVPRO of Carroll County a call at (410) 857-5332. We can give you that piece of mind that everything is okay or we can mitigate and get you back to breathing easy.