Ok, mystery has been solved.... kinda
Whilst in the queue for my MOT Becky from Bicester phoned me back to explain.
Apparently the outlets sometimes get batches of bags that are all marked 0, but are inspected and are absolutely perfect. They can then sell the bags as perfect and post them out. It will show up on their system as marked 0 but perfect... confusing, much? So it will not affect my warranty etc. All the bags they have in the cotton weave have the 0 so I'm no better off with another one. And I do love my girl!

But when I have phoned the outlets in the past I have only asked, "is it postable?" but now it seems you run the risk of getting a 0 bag... maybe we should being more clearly asking is it stamped 0.
She also said they don't tell customers because most don't understand this system and they don't want to alarm anyone. But, I'm thinking really they should explain in full to every customer... what do you guys think?
I couldn't talk to Becky for long because I was going to be called for inspection.
So, yes, my girl is a 0 but she's staying put