Exactly. I have run into this problem with event calendars. For example: Schedule a recurring event for 1pm. It happens to be EDT at the moment so you store the event date/time in UTC by adding 5 hours. Then, in days, weeks, or months, we change to EST. The 1pm meeting is now showing at noon.

To fix this I run a cron job on the ST/DT boundaries that increments or decrements stored date/times in the event calendar.