Hi musicaljoke, I am a trained musician (former professional violinist) and all the notes on the fabric are depicted accurately, as far as I can see. Some of them are upside down or rotated somewhat, but they are nonetheless represented correctly. In real musical notation, the stems can be above or below the main part of the note, according to where the note appears on the stave. For example, high notes normally have stems pointing down - if they pointed up the way it would take up too much space above the stave, and large gaps would have to be created between musical lines; conversely, low notes normally have their stems pointing up.
The stems normally adjoin the left side of the main part of the note if pointing down; the right if pointing up.
It's all to do with what is easiest on the eye in terms of readability when you are playing a piece of music, and of how tidy and compact the notes look on the page. I found this clip:
[video=youtube;oPBxTcYfh5w]https://www.youtube.com/watch?v=oPBxTcYfh5w[/video]
A bit off topic, apologies folks! But for what it's worth in the context this case I think the fabric maker knew his or her notes...
Wish I could contribute something a bit more constructive - amazing work here today by everyone!