I have run into the same issue and here is what I did to resolve it:
Add the following before the first function:
Not sure if this is the best place to put this but some of the other places I tried it didn't work or only worked for certain parts of WordPress
Another way to approach this is to let php know
what your time zone is. You can edit your php.ini file and put in the
date.timezone = "America/Anchorage"
You can find valid time zone strings at http://nl3.php.net/manual/en/timezones.php