What you're missing there is what the temps were that night and which version of that quilt you had. Also whether the quilt was actually the right size for you - people of a heftier build can have issues with regular size quilts wrapping around them well enough. JRB makes the larger quilts and also quilt wings that help you tuck in more firmly.

I have three season Hudson Rivers, have slept down to the mid20F temps in them reliably without issues, and without a bivy. But I'm usually in a hammock or a tent of some kind, and the quilt will wrap around me without quilt wings.