Good catch! They didn't quite look right. I was able to make them look a little better by tweaking the sizes by a few pixels. They still don't look perfect, but it seems this may just be a trade-off to using an image instead of an HTML table.
They're a lot better now, but still a few dots aren't square.
The QR code is 145x145 pixels.
It has a 12 pixel white border around it.
The data area is 121x121 pixels.
There are 41x41 dots, so almost all dots are 3x3, but two rows and two columns are only 2 pixels tall/wide.
Make the whole image 2 pixels wider and taller and it should look good, since 123 is a multiple of 41.