Yes, I've seen that .tmp file creation happens just from Ctrl-S. I meant does "the disappearing .sas file" ever happen just from hitting Ctrl-S? That would be scary.
For me, it seems that I end up with a permanent .tmp file about one out of a hundred (or thousand) presses of Ctrl-S.
So at the end of the day, I may have one or two .tmp files in a folder. I habitually press Ctrl-S when I pause to think.
I suppose any time the .tmp file has a time stamp newer than the .sas file it was intended to replace, there's a risk that I could close the .sas file, and later open it again, and not realize I have lost one iteration of edits.