When working with borders is is far more likey to have them go wonky .. if you are using cross -cut/grain fabric. The cross cut stretches. Lenghtwise grain has very little stretch. The problem will magnify the wider the borders when using cross cut. There are times when I just can not bring myself to use lenghtwise , particulary for a skinny border. In those instances I starch the ..heck out of the fabric prior to cutting. I then pin the border(s) while the top is laying completely flat so I do not inadvertantly stretch while attaching.