Nope, nicks don't form part of a k:line. The mask is [email]user@host[/email] rather than nick!user@host - at least I do believe that is the 'standard'. However the fact that you changed your user id (ident) could be the contributing factor as the ban may include the actual user id you previously used. If the oper saw you get around the ban that way though it is entirely possible that you would get nailed again with a *@host, the mask I routinely use myself anyway which would mean that no matter how many times you change your user id, you wouldn't be able to reconnect.