Adding a panner and a flipbook node

Getting some unexpected behavior when adding together a panner node and a flipbook node.
Flipbook animation should look like this:

71681-battlediamond.gif

And it works fine normally, but when the outputted UVs are added with a panner UV, odd results occur:

https://dl.dropboxusercontent.com/u/85252715/Desktop%2012.23.2015%20-%2002.19.19.05.mp4

As you can see, the flip book animation becomes jittery and inconsistent. The particularly strange part being that only some of the tiles actually turn out perfectly fine.

Is there a way to fix this?