We typically have users working with Google Calendars, so I did some digging for Apple Calendars.
I noticed that when I imported my Cal code from Apple, I had the same problem! So I followed some instructions I found, and found out that although my local calendar is set to Eastern (where I live), my iCloud Cal was set for Pacific.
Can you go to
https://www.icloud.com/
And log in
Then, click on your name in the top right
Adjust your timezone as needed
(http://support.apple.com/kb/PH2614?viewlocale=en_US)
You can also click on the system preferences there and turn on Time Zone Support, then refresh your calendar, and give it a few hours to sync:
http://support.apple.com/kb/PH2677
We are troubleshooting together, so please let me know the result after a few hours, once the calendar has had time to sync back up.
Cheers!