I had this issue too on my iPhone, except I'm in Canada and it changed my time zone to 2 provinces west. I was fine yesterday, then toward the evening noticed I was an hour out with it automatically set to another city. This was before I did the OS upgrade. After doing the upgrade, still had the same issue and tried everything on these message boards. Only thing that worked for me was this from the apple site:
Select a different city (other than your closest city) in Settings > General > Date & Time > Time Zone. Turn off iPhone, then turn iPhone back on.
I chose a city in a time zone east of me, turned off my phone and back on, then changed the setting to automatic and it finally came up correctly. Tested with my email, etc. and times are now showing correctly. Seems like no single solution works for the general population so I guess you've got to try different things. Some got it to work correctly by turning Airplane mode on/off or a hard reset.
Good luck! Apple needs to fix this issue. Strange since I didn't have it during the last daylight savings time though.