I recently updated the Canvas URL in my Facebook App, I changed it from http://www.domainname.com/subdir/ to sub-fb.domainname.com/. For some reason it will randomly switch between the 2 urls on different visits. Is there some kind of Facebook cache that needs to be cleared? I made the change 2 days ago.
Thanks!
this ended up being an issue with facebook round-robin caching, just had to wait it out