Certainly possible. I'm still in the camp that it was just a damaged/broken "E" stamp used for a place holder for the upcoming addition of the A, B, C.. Although we didn't see them until Oct (forgive me going off memory) so idk. I need to look but I don't believe I have any early 69's with the "c" on them.. As you said it could have been a quality check also.?. But why only do it for a few months in production.. Definitely a head scratcher.