Re-discovery of the Maya UV editing bonus tool!
This was a great way of creating quick border edges.
Not sure what happened at one point, but I managed to actually select and create two unwanted border edges, randomly on the shins. Took a while to find and select them, but once found, even though it wasn't possible to delete a border edge, I was able to shift select and choose the 'merge border edge' option...
I've put this checkered material on the model, so I can see how the UV map is laid out and scaled...