Nginx – php-gd installed but gd not showing up in phpinfo on CentOS 5.3 server running nginx

Logged in as root, I installed the php-gd libraries using

$ yum install php-gd

it said everything worked fine, so i did

$ /etc/init.d/nginx restart

But the code I had been working on still complained of not having the gd libraries and when I went to check the output of phpinfo there was no 'gd' section.

I should note that yum list | grep gd shows

gd.i386  2.0.33-9.4.el5_1.1  installed
gd-devel.i386  2.0.33-9.4.el5_1.1  installed
gdb.i386  6.8-27.el5  installed
gdbm.i386  1.8.0-26.2.1  installed
php-gd.i386  5.1.6-23.2.el5_3  installed

I also added extension=gd.so manually to /etc/php.ini and it is still not showing up or raising an error which leads me to believe my php.ini is not being re-parsed when I restart nginx. Is there something outside of restarting nginx I have to do to get php.ini changes loaded?

I have a fair amount (like 3 years) of ad-hoc server administration experience although no formal training, but I'm relatively new to nginx and have never worked with CentOS before, so any help would be much appreciated.