(i didn't use WinSCP a while, so that is why i noticed it only on this moment, and not earlier ;))
after doing some research, i found out that this was most likely a timestamp related problem.
so i tryed to change timestamp settings, but that resulted not in the correct behaviour. local timestamps where off by 1 hour (GMT+1 zone) and remote ones where ok, or vice versa.
after my blood pressure rocked through the roof and some cooling down time later, i realized this:
i had running WinSCP running in the background for 3 months (and the (lan) connection stayed alive too for 3 months, good job !), so maybe the date/time info in memory whas not correct.
so, i restarted WinSCP, and everything is ok now :)
suggested bug fix: please reload windows timezone info when DST is enabled/disabled, or periodically check if the timezone info has changed.