In #3028, some of the machines were having a bad day.
It is does not take too long to fill out one of the blue forms--I once got an "X" on my GE form and having one filled out in advance saved me some time.
I've had the "X" twice - I've never been asked to fill out a blue form. The CBP officer asks me questions, then stamps the "X" form and sends me on my way.