Apparently there are people who don't know that the Daylight Savings Time (DST) changes this year foisted on the American public by the Shrubbian Empire are also applicable in Canada.
Many people who do know about the above don't know that some applications keep their own DST tables separate from the operating system. Java is one example.
Many more people than either group above don't seem to realize that most real operating systems use GMT internally and apply time zones only for display/calculation purposes. So yes, while we synchronize machines using NTP they're still going to be an hour off if we don't patch them, because one is applying a time zone of EST and the other is applying a time zone of EDT.
Consider yourselves edumicated.