Strange vertical offset of text with Imagecache Text Action

I've got a caption item (the title tag of an Imagefield) that I'm displaying on images, and I am getting a strange vertical offset of the text on some of the images. I have attached an "ok" version and "offset" version to this issue.

The SVG style I'm using is as follows:

font-size:11px;
fill:#ffffff;
background-color:#000000;
top:bottom-53px;
left:0px;
width: 320px;
height: 23px;
padding-left: 10px;
padding-top: 6px;

This is on a preset that applies actions in the following order:

1. Scale and Smart Crop
   320x240
2. Sharpen
   radius: 0.5, sigma: 0.5, amount: 100, threshold: 0.05
3. Text
   "return $file_data->title;"
   font-size:11px; fill:#ffffff; background-color:#000000; top:bottom-53px; left:0px; width: 320px; height: 23px; padding-left: 10px; padding-top: 6px;
   LiberationSans-Regular.ttf

Any idea why I'm getting a strange offset? Does it have to do with the padding-top rule? Is there a rule for vertically-centering the text in the render area that might be more appropriate?

Thanks for a great module! I hope to get this one item sorted out soon (and hoping it's something I can change on my end).