When a USB drive is inserted into the port on the i3 Mk4, its contacts face to the left. The icon that appears shows the contacts facing to the right.
Completely non-functional enhancement, but at least for me it's one of those things where once you see it, you can't unsee it. Detracts a tiny bit from overall quality/finish of the product.
I'd be happy to fix and make a PR, but so far as I know you haven't released source for this printer yet.