As you all have found - we expect that some people might have to file them down.
We found huge variations in the width of usb ports - we want them to be tight because that helps them stay in place without a conventional plug, so we tried to pick a width somewhere in the middle that would work for as many as possible.
As duckythescientist said well - this is certainly a device for makers, and we made sure there were no traces on the USB connector edges, so file away without fear of breaking them!