We have something similar to that happen at our field alot. Groups of people will come and play when we set up to play. Every group seems to have a leader, and if set leader can't make it none of them will come. Now these aren't people we've never played with before either. Most of them play like every 2 weeks or so, its to the point that everyone is on a first name basis.
I just thought this was kinda weird.
trix with halo and 68/45 crossfire
7man airball field