I haven't tried taking out the mods before unregistering manually. I will if it happens again.

I was (in a sinister manner) hoping nobody would post about this.
In the Mac version, if you firewall CC or it cannot connect to licensing servers, it decides you are registered.
For instance, turning off your wifi, with no other connection. You can also use the built-in firewall, controlled via the terminal to do the block.

I may have been playing using LittleSnitch to keep CC from even seeing a network to talk to, let alone utter a single ping.
It's ironic, as LittleSnitch itself is a demo, and that only lasts 3 hours before it nags you…

Well, I'm probably safe for the time being, as the release cycle is nice and leisurely.
Cat's out of the bag, here's data about it.

I've tried registering with the network on using this key and mail, and it (duh) fails.
The glitch cannot be reproduced by my windows friends at all.
It might be just because the Mac version assumes you are registered, rather than unregistered.
There is no data in settings.ini at all, the instant there is (like putting this in) it will deem you unregistered, regardless of connection.

I highly reccomend bluring that image.