Alicia, who actually knows the answer, can't seem to log onto audiodrama, so I will try to pass on the info.
"The answer is that PodPress tracks the number of downloads and masks
the actual download URL by putting up a 1kB reference file in the
podcast's feed: http://www.themaskofinanna.com/feed/podcast/
This file typically refers the browser to the actual MP3 but it sounds
like in this case, the iPhone is only downloading the reference and
treating that as the MP3 file.
The solution would be for us to disable the tracking and URL masking
features on our site."
I hope that helps.