There's a thread on the theme park strategies forum about people having issues with
Walmart in particular withholding photo service because of copyright. People even with the CD and the copyright release. Perhaps you should check them out.
I personally have used Snapfish for my photo developing and haven't experienced any problems with them. It seems to be a print in store/pickup issue.
Hope this helps. Sorry to scare you if you did. On the up side, there are so many people who have used Photopass without issue!