Since the author span is under the h1 text, I would try moving it outside of the h1 into its own div. Then you can try using normal (not absolute) positioning to see if that makes a difference.
<div id="sp_graphic" class="BG_about">
<h1>Acupuncture is the greatest gift<br />I've ever given myself!</h1>
<div class="author">K.R. Palmer, AK</div>