There is something wrong with it.....because I didn't last chat to that contact at 00:40, I last chatted to them at 11:40, so the information is correct. The change in time in the present doesn't affect the time in the past....so it's correct in saying that it's a bug.
And yeah, I know the time stamps in chat-logs won't have been re-written, but I was just saying it for completeness....and it also further highights that it's a bug