I had this issue with my ADRs as well. Showing up one hour earlier than the actual reservation. Then I noticed that the reminders I'd set up for parades, etc. were also an hour early. Before checking here, I did an online chat session with a CSR on the Disney site. She claimed that there was no advisory about this problem and told me to talk to Apple (yeah right). I quickly pulled up the disboards site and found this thread. I gave the CSR the link to the thread, but she said she's not allowed to look at non-Disney affiliated websites. I told her to tell someone who could check the site to do so, and she said she would, but who knows.
Lesson learned: I should have come here first!