I think it is always encouraging to see our young ones worshiping.  In our church and most all churches Sunday school is valued as a critical place to teach the love of Jesus in a smaller, age appropriate environment.  I'm sure your congregation was thrilled to watch the children.  Our church has not done this in a very long time and your post helped light a fire for me to talk with our Children's Director about seeing this through.  I think the children leading the elders helps us all to loosen up and rejoice for Jesus together...no matter what age.