Note that default has a moss abm, too.
It puts moss on every cobble node next to water, so it does neither test if the moss can breathe (i.e. air is next to the node), nor does it heed a minimum distance between two moss nodes.
I recommend you to disable the default moss spawning at default/functions.lua:650 (the line number may be inaccurate) while using this mod.
Supports: default, stairs
License: WTFPL (maybe except the wet gravel texture)
Download: zip, tar.gz
If you got ideas or found bugs, please tell them to me.
How to install a mod?