The frolicking dolphins are eager to welcome Wilbur to the watery grave he keeps dodging
Six Chix, 5/11/23
So the thing about "sudden," as a noun, is that it has completely fallen out of use in English outside the set phrase "all of a sudden," and even when it was in use there wasn't any particularly strong syntactical or grammatical reason why it took an indefinite article in that phrase rather than a definite one, so it's pretty natural for modern-day speakers to start reanalyzing and rearranging the phrase, and as long as people know what you mean it's hard to say you're doing it "wrong." Still, some people care a lot about being right in linguistic matters; I found this out the hard way when I got into a discussion on the comments of this very blog in which I pointed out that "none" is not a contraction for "not one" and has always been used in both the singular and plural, with recorded uses of "none are" going back to Chaucer, and this caused one commenter to melt down at me and then quit the site altogether. I have my own odd things I'm overly attached to, of course, but at least none of them have me visualizing myself as an angry pulsing green blob holding the line against a bunch of purple blobs that look pretty chill, honestly.
Barney Google and Snuffy Smith, 5/11/23