It's too bad, but a reality that we have to worry about the safety of our children even at church and clubs. But it is best to deal with the problem as best you can in a way that will discourage those that would abuse children from even thinking that they can get away with it. Many churches and organizations have adopted "Child Protection Policies." In my own church every children's Sunday School class must have a second adult, not related to the first, present in the room.
For the sake of the children, establish a policy, even it is just a "personal policy," that will both prevent the occurrence of abuse and protect you from false accusations.
The example mentioned of a second adult makes sense. Physical contact must also be considered. A church setting is usually more relaxed and family-like and many children will run and hug a teacher they have grown to love. But be extra careful not to be too physical with visiting and new children or those in a more public setting.
Be sure to conduct yourself in a Christ-like way with the children in every circumstance and expect co-workers to do the same so as to honor the name of Christ and to watch out for the well-being of the children.