codeigniter routed segments incorrectly converting dashes to underscores with nginx

[eluser]jayhung[/eluser]
I have found the problem - developer error. The deploy script in use was not properly deleting an old MY_Router.php file from the server (this file did not exist locally nor on the apache installs).

Codeigniter, PHP, and nginx are all working as expected.

Thanks all for the comments.