If your side borders aren't the same length (or your top/bottom border aren't the same length), and it's only 1 1/2" inches-- then I'd split the difference and ease in one side border and stretch the other side border. Over the length of the quilt, its only 3/4"! That's not much for a bed size quilt. Usually for a border I measure the center of the quilt and go with that length, rather than measure the edge. That keeps the top flatter. If you don't mind the quilt not being squared up, just go with it. No one is going to notice your spacers. You put them on the ends, right?
If you have 3 short borders, I'd take out the good one and ease in the same fillers on it as the other 3, so that all 4 borders match.
Last edited by givio; 12-14-2017 at 08:42 AM.