There are bound to be little tweaks like this that come to light - OpenGL was dropped a while back and is just now making its way back in. And in that gap the terrain system changed - twice.
It's probably going to come down to little fiddling differences between drivers, but I hope not.
Unity has a 200+ page bug list, UE4 has issues and I don't mind getting my hands dirty for Torque3D.
Seams are solved for my project though. OpenGl works great for me on Win8.1. Can't wait to fire up a vm and test Linux.
The seams were the only thing that cropped up and I finally fixed that.
I am happy as long as I can craft a solution or workaround for an issue.
Whether the uv offset is a solution or just a workaround, that's for the real
devs here to decide