I think they mean that, out of their first 500,000 members, you were one of the first to register in Iceland. As in, you were one of the first people in Iceland to sign up for LinkedIn, and you did it very early.
"You were one of our first 500,000 members to register in Romania." He may be not out of their first 500 000 members and i think that applies to me too :). Something fishy with this message ... Result, no importance given or we both could call linkedin contact to see what's this about.
