All the options were granted at the same time - this is just the vesting schedule. 1/4 of it vests in a year, than the rest vests month by month for the next 3 years. Simple math, and very normal.
Almost any time you see a whole bunch of From 4s from corporate officers and/or Bod members on the same day it is because options have been granted (and some possibly exercised immediately to make the transaction tax neutral).
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