Incorrect presentation of an event between 26/10 and 31/10 (daylight changing)

Our users reported a strange bug. When an event is added between 26/10 and 31/10 when you click on it on the calendar it appears as it was added a day before. This only happens between between 26/10 and 31/10. On any other day, events appear fine.

The system we use is an Ubuntu (64 bit) 14.04.
I tried replicating that on demo.moodle.net but i couldn't. any clues?