Alarm on IPhone 4 + timechange (Summer -> Winter) = alarm goes off 1 hour to late

An alarm for 6am on weekdays was set and used before time change from summer till winter. On the first weekday after time change it went off at 7am.

A new alarm was made for 8:30am and it went off at 8:30am.

It sounds like a summer/winter time problem.

Does the alarms go by USA's time change? We will see monday.

Or how is it set? Doesn't look like it is set independent of summer/winter time.