My wife grew up in England. She says "et" for "ate" quite a bit. It's not just a rural American thing. Or did you grow up in England too?
Cheerio, mate! But acutally, no. I think it's some sore of colloquialism carried over from years ago. I've heard some old time geezers refer to the county sheriff as the "high sheriff" which I think is a Brit thing also.
David Suchet ("Hercule Poirot") has an excellent audio version of the NIV Bible. In it he, too, pronounces "ate" as "et". IIRC, he is also a stage Shakespearean actor, so he probably knows "the Queen's English".
Bahama Islands, too. I once mistook NASA’S robo-voice for a Bahamian.