dynamic text replacement-text images not appearing properly

Hello,

This is my first post on Drupal so forgive me if I'm in the wrong place.

I maintain a site that uses dynamic text replacement for titles. The problem I am having is that the text images for all new titles are suddenly not appearing the way they should- as if the bottom 2 0r 3 pixels have been "chopped off". They are also not aligning properly. Here's an example:

http://longevity.stanford.edu/node/695

I say "suddenly" because it worked (almost) perfectly until recently. In fact, all of the existing titles look fine. It's only when I try to edit them or create new pages that this problem occurs. The only "event" that may have caused this- that I can think of is a recent upgrade to PHP 5.2.10.

I've done some inspection with Firebug and it seems like the problem is with the vertical alignment of the text within the image created.

I've spent hours trying everything I can think of to no avail, so I'm hoping someone out there can help me. I can't post any new content until I get this straightened out.

Thank you!