Ah, thanks. The 'smaller than what i usually work with' size condition narrows it down where to look, and sounds plausible too.
I haven't been able to replicate it yet, though.
Was the file you saved to also an .nss? or something else?
Let me know if you encounter it again (though it sounds like having opened it in a new program instance may have flushed the issue away - which is good for you but troubling for me haha).