thank you for letting me take a look.
One solution is to add a few lines of code for instance to the style.css file of your theme or maybe to the /podpress/style/podpress.css file.
The following lines should help:
It seems that your theme enlarges images in the featured post and since the icon is an image file, it increase also the size of the icon.
But note that if you put these lines of CSS code in a file of your them or the podpress.css file, updates of the theme or podPress will overwrite these added lines and you would probably need to add them again after the update.