Gallic civilian tech is free to leave with Gallic corporation IDs. I can grab my GMS ID'd Vache and go wherever I please, for the most part, just like any other Sirian. Same goes for EFL and IDF. Sunbeams and Moonbeams, the Gallic civi ships can come and go as escorts to those same transports.
As far as I understand, GRN ships, such as the Caracal, Serval, and Lynx can only leave provided that they have been granted via tech requests to a player wearing a Gallic Corporation ID and are escorting Gallic transports.
So, again, Gallic Lawful snubcraft only leave Gallia as escorts to Gallic transports. Gallic Corporation Transports are free to move as they please. GRN and GRP forces, however, no matter what they fly, are prohibited from leaving Gallic space.
Of course, that's all rule-specifics. Don't expect too many people to be happy to see a Frenchman running around their space.:P
What ship were you on yesterday when the GMS boys came though? I was flying the French Advance. I'm still surprised how few people realize that Gallic corps are free to move about the sector. There was a pinned thread on it in the Rules section for a good period of time. I do like running about, though. I imagine you'll be seen a lot more [GMS] in the future too.