It makes you wonder. According to Fritz Springmeier, the real birthdate of Jesus is 9/11 (worked out from when the star appeared that the kings supposedly followed to Bethlehem). His interpretation is that they place events like 9/11 on that date as a sort of triumph over Jesus, to show that he doesn't rule at all. It's possible that 33 is significant to them as a straightforward way of celebrating his death, although it could also be a coincidence. They've got to be quite obsessed with Jesus if the whole structure of freemasonry is based on Jesus's age when he died.