Interesting and probably known to all but me. I am working with a model in openscad 2013.06 on Windows and after a small change in the code, F6 re-render, and export to STL #KISSlicer starts warning me about “Only 1 triangle shares this edge”.
Fine, I am used to this when working with OpenSCAD and while this probably can be repaired with #NetFabb or maybe even printed ok with the error I REALLY don’t like #errors in my models (which probably is why I never get anything finished 
So anyway I undo the code change, F6 re-render, and export to STL. Still the same error! After spending way too long trying to find the cause I try the version I saved minutes earlier and no problem.
I make the same code change and again the error appears. So I save the file with the error and restart OpenSCAD completely, re-render it, export and NO ERROR!
Design (menu), Flush Caches will also get rid of the error instead of a restart so I guess OpenSCAD caches stuff which aren’t guaranteed to update/change just beacuse you change the code that directly or indirectly made the error show up in the first place.
So lesson learned: If you get an error from a file exported with OpenSCAD, and believe you have fixed it or if you just really want to be sure to get a fresh export before sharing a final design STL - FLUSH THE CACHES, F6, export to STL!
Annoying.
