timestamp skew during 7.4 -> 8.2 upgrade

Hi,

After our 7.4 to 8.2 upgrade using debian tools, we realized that some
of our timestamps with tz had shifted:

For example '2007-04-01 00:00:00+02' became '2007-03-31 23:00:00+01'
which is on a different month. Some of our applications were severely
disturbed by that.

Has anyone noticed that? Is there a way that would could have avoided
it?

Thanks,