Apple has acknowledged an iOS 4.1 bug involving daylight savings time in some countries. In an online note (http://support.apple.com/kb/TS3542), Apple had this to say:
“In some regions, shortly before or after the daylight saving time (DST) change, repeating alarms created in the Clock app may work incorrectly.
“Products affected: iPod touch (4th generation), iPod touch (3rd generation), iPhone 3G, iPhone 4, iPhone 3GS, iPod touch (2nd generation)
“To resolve this behavior for existing alarms, set the repeat interval to Never. You will need to reset these alarms for each day you need them. After November 7th, 2010, you can set your alarms to repeat again.”