yeah, that happened to my mom once. when we got to check-in, they didn't have a problem, they just changed it, and then she was able to go to the purser and get a new card with the correct spelling of her name.
Let your TA know right away, so that Carnival can be notified. You don't need a new set of documents, but your name must be spelled correctly on the ship's manifest, which must be submitted to Immigration authorities 72 hours prior to sailing.
I'd have them correct the misspelling. The whole new security thang means that names need to match-- gender too. My toddler daughter's ticket labeled her as a boy (no way you'd ever think that-- she's a frilly girly girl) and we had to have it changed with Carnival before we sailed for security reasons.