Correct me if I'm wrong, but in order to get a true Grand Slam, you have to win all 4 majors in a calendar year, of which the Masters is one. He lost the masters yesterday by a few strokes.
I'm presuming that because of the time-zone difference in Australia, yesterday hasn't reached you yet, and therfore you haven't seen him play the final round
But can he do it in the future? Quite possibly. Will he beat the current records for most majors won in a career? I'd put money on it.
Cheers,
TMC