Spline Mapper Grayscale node does not work as expected

Hello there!
While i use the spline mapper node its behavoir is pretty strange fo me. It seems there two issues:
1. The 0 height of splines is not considered as real 0. So if i blend (multiply) the height and the color outputs of this node, the exteme point are still visible (but their height is 0)
2. "No-tile" mode is not working. all my node are no tiling mode but the extreme points os spline mapper are still tileable. 
I put the spline render node to see the difference.