Newbie Q: ship placement in combat?

[Maerlyn]

something very strange happened to me in a PBW game recently. usually if you fly trough an enemy occupied warpgate his fleet will be gathered around the warpgate (as will yours) and he will have first strike. this is very strong, defense wise.

but recently I entered a warpgate which was defended by three enemy races. I started the combat in the middle of the map (close to the warpgate) but ALL three of them started the combat in different corners. although they still had the first move.

now since their fleet was split up in three parts it was an easy win for me.

any ideas why they werent placed at the center?