Not sure what the problem was but here is what I did that appears to have fixed it -
1) copied the rss feed to a text editor that display line and column # info
2) scrolled down the file until I got to the line/column where the error was from podcast addict.
3) didnt see anything that looked like a problem but replaced the entire line from a backup copy that I have
12 hours later and all podcast clients on the different distribution points (google, itunes, etc) appear to be working normally.
hope this helps someone else if/when they run into the problem.