I think it was around 2005/6. I have a 2003 that doesn`t have it. If everything else is in order I wouldn't worry.
There are discrepancies between markings on earlier and later bracelets too. I had two Bond bracelets, both genuine, but the Omega markings on the clasp were significantly different. I guess two suppliers were used, or maybe they changed for no good reason?
If this was Rolex a book would've been written by now and the sages would be stroking their beards whilst expounding their extensive knowledge.