Hey Chris,
The time zone for ga:hour is configured per the account settings and
respects local day light savings time.
During the daylight savings time change over, there will be an
apparent bump in the number of visits between 1:00 and 2:00 (or
whichever the hour is) for the day per year in what that hour
repeats. There will be a corresponding hour with zero visits at the
opposite changeover.
-Nick