It says a new character is the first character on your account to reach past lvl 5 (IE: lvl 6). I have 5 Characters on my account. I do not remember which was the first to hit lvl 6, but I do know one thing. All 5 are under 25 and all 5 do not count as a new character. So how I am to recieve this newly added bonus for new characters if none of my characters count?
What bekkar means is that if you got a character past level 5, that one is your 'new character' and if you delete it, you have no 'new character.' The deletion does not make the next lower character your 'new character.'
If you have never deleted one, and the Newbie Guide does not recognize ANY of your under-level-25 characters as a 'new character,' that is a bug. Petition a GM, and send an email to support.