That half leaf is probably the flower sheaf which will not grow to be a full sized leaf anyway. This is where the new spike will emerge from so it is good that it has reached maturity. If the roots are good and the plant seems healthy then you will just have to wait until next Autumn / Winter for it to bloom for you. Mine missed the season this year so mine looks like yours does, several long leaves and one short sheaf. They should bloom for us next year.