I can only remember ever coming across it in a short story by Raymond Carver: Bicycles, Muscles, Cigarets (1971ish). I imagine he was making some point about one of the characters by spelling it that way ~ it's a very long time since I read it.
Agreed. There were a few things like that, where there was a group of AE speakers perferred the -et ending ove the -ette ending, that I noticed when I moved from BE-landia to AE-landia. It doesn't look as though they were ever a very large group
(Omelet and pipet are the only ones that come to mind now)