Something was wrong with it. everything was dead for a while, and all of a sudden at exactly 1300 my time, feed started playing and the 503 message disappeared. My thought was a server went down for some reason.
Yes, I had trouble this afternoon as well. I just happened to reboot my computer and when it came back up, ScannerCast couldn't connect. I briefly thought it was something on my end until I realized I couldn't get to radioreference.com in my browser or listen to any other feeds.