Maybe a cross-timezone interaction? 23:00 pacific is 02:00 eastern (most days)

Right, the transition to daylight savings at 2AM in the Eastern time zone occurs at 11PM in the Pacific time zone; there is one less hour's difference between the time zones until the Pacific time zone also springs forward three hours later.

Towards the bottom, it states:

  It turns out that the Pacific Time Zone is the only one where the bug caused a user visible difference because:

    1. Daylight saving time starting or ending changes the time zone offset by just one hour.
    2. The bug only has an effect when the difference in the number of hours goes from less than a day to at least a day, or vice versa (e.g. 23 to 24 or 24 to 23).

  The only hour of the day that satisfies those two conditions is 11:00pm, and the only time zone where daylight saving time starts and ends at 11:00pm is the Pacific Time Zone.

The article may state it, but it's not true. US DST starts and ends at 2am in every time zone. It doesn't start at 2am in the east, 1 central, 12 west, 11 pacific.

Yeah, even the Wikipedia article the article links to claims that the transition's at 2AM:

> North America coordination of the clock change differs, in that each jurisdiction changes at each local clock's 02:00, which temporarily creates an imbalance with the next time zone (until it adjusts its clock, one hour later, at 2 am there).

DST is 2am in Pacific time zone. The article doesn’t make much sense.