It sounds like the network allows X amount of time for you to join a channel after connecting to the network, and if you aren't in any channels after that amount of time, it forces you into the #orphans channel.
This is getting to be more common in order attempt to control bots that join the network and use network resources without actually joining any channels.
Some networks are actually going to the step where if you haven't joined at least one channel within X seconds/minutes of connecting, you get k-lined.
