I started quilting in about 1978, but I was sewing since 1964. When it came to calicos and other small prints they always seem to be the same for years and years, especially if you shopped at Ben Franklins, TG&Y, Woolworths and Newberry's. And also, like now people had stashes. I bought (and still have) 5 yards of a rose cotton fabric when it was on sale for $.25 a yard. Every so often I find a similar print now. So just because someone bought the fabric in the 70's doesn't mean that it was a new fabric. My sister had a store near her home in Rialto CA that was a true outlet for unsold fabric. They had bolts of fabric they sold for $1.00 a yard. A lot of it was great cotton fabric and some of it could have won "the Ugliest fabric" contest. Even at $1.00 a yard it was too expensive - but people bought it for various reasons.
So I am very sorry those people found it necessary to challenge your knowledge of the quilt. There is no excuse for them.
Thank you for showing the finished product, your quilt looks fantastic and the lady that pieced it together must be thrilled too.