While Apple is busy finding nifty little improvements to the latest iOS 4.2 operating environment, they certainly have missed to fix the alarm bug in iOS 4.2 GM update. This bug prompts the operating system to ignore the Daylight Savings (time changes) with the in-built alarm application. It affects the iOS devices on which alarm is set to repeat on certain days, like weekdays, when you rely on your Apple device to wake you up in the morning for office.
However the fix for this bug was expected to come with the latest iOS 4.2 update but unfortunately it didn’t happen. So for the time being to fix this minor glitch you’ll have to open the alarms, save them again by re-toggling the timing and thereafter rebooting your device. After restarting the alarms will work just fine.