I think I've found the problem, but I don't know what caused it.

I did a Show Source for the http://www.debrasglasscraft.com/gallery/index.php page, and this is how the url is reading there:

<div id="logo"><a href="http://www.debrasglasscraft.com/gallery/"><img src="includes/templates/template_default/images/http://www.debrasglasscraft.com/gallery/images/logo-large2.png" alt="Debras Glasscraft" title=" Debras Glasscraft " /></a></div>

I'm thinking that the easiest solution is to copy the logo-large2.png over to the includes/templates/template_default/images/ folder, then change the full url in the header.php file to just logo-large2.png.

Either that, or I could just alter the header image, adding the logo inside it...