I've received mixed answers on this:
  -- Some users in the Community have said their time updated automatically, while others say it did not.
  -- A Marketo support rep told me it 
doesn't happen automatically. (I opened a support ticket about this)
  -- Another Marketo employee said the GMT offset time 
does update automatically in the regions that use standard or daylight time at different parts of the year.  (see more here:  
https://community.marketo.com/MarketoIdeaDetail?id=08750000000KIhGAAWSo the non-clear-cut answer I've come to is....perhaps for those of us whose time didn't update automatically, we had our org set on an incorrect time zone prior to the clock change.