1. Make sure you have the latest version.
2. Open the gridstatushots.lua file in your interface/addons/gridstatushots folder with notepad.
3. Search for the following line:
local bname,brank,btexture,bcount,btype, bdur, bexptime, bismine = UnitBuff(unitid, i)
4. On the line directly underneath it paste:
if bismine == "player" then
bismine = true
bismine = false
Tested just now in Ulduar - other druids HoTs are no longer showing on my Grid.