i have the same problem going on...
little brown spots that seem to just disappear ond leave a hole in my plants leaves.. i thought it was just the one plant but now that i have looked all over them all it seems to be wide spread (8 of 12) and seems to start as a light-ish green almost scaley look then goes to yellow then brown then the 'dead spot' as i am calling them go away.. and leave a hole in my leaves.
sound familiar?
hope we can figure this out..