I can't recall if this is how it was before, in previous versions, but it seems something was done to the sliders behavior in version 19, because people have reported big and unexpected and often unwanted jumps in using mouse scroll wheel with many sliders in the color page. This could be related to that.
I never really used it like that, because I think it was meant to be used with proper hardware wheels and control panel, rather than mouse, so I tend to move the mouse over numbers left and right or enter number I want. That's why I can't remember if this is how it always worked, but it seems to be same in other three options in the same blur panel. Mist and sharpening.
I also noticed inconsistency even among OpenFX filters. Like mosaic blur sliders. When using mouse scroll wheel.
