The Bluebird of Confusion

I was looking at the Peanuts comics site late yesterday to see the Sunday comic, when all of a sudden I was more or less doing a double take: although familiar with one of the first "your brother pats birds on the head" comics, in this colour version of it the bird was blue, beak included. Now, there would still be years of design evolution ahead before Woodstock, who we all know to be yellow, got named, but it was still somehow strange, almost unnatural... I first managed to remember how I'd taken notice of a reference to a "blue jay" in the 1963-1964 complete collection, but then, in the midst of wondering if Charles M. Schulz's colouring guides from the early 1960s still existed, I happened to also remember that I've seen a Peanuts storybook cover also with a blue bird on it. Probably that reduces the whole thing to a curiosity.