There is a topic about Orphan blocks already on this forum.

https://bitcointalk.org/index.php?topic=940943.0

The conclusion comes down to: low difficulties ( Like with XVG coin ) + Big hashrates = Orphans ( +/- Duplicate block elsewhere found on the planet at the same time )

It is on our monitor and we are watching it closely. In anyway, other pools experience the same, it's just a matter of luck (or not) and over a period of days it will level out. Secondly, we are far from loss. The pool is running about 135% of what you should get, with orphans.