The daylight saving time, if switched from "no" to "yes" doesn't skip an hour, instead it adds an hour to all post-times.

For example:

• if you wrote a reply yesterday on 3 p.m.
• then switch dst on
• the reply now appears with a post-time from 4 p.m.

But that is simply no true. The real post time is still 3 p.m. and so the DST Switch should behave.