Morning Glories

My Morning Glories were, all season long, blooming this beautiful purple called Grandpa Ott's and also a lovely deep pink from a different seed pack. 2 weeks ago, on the same vines as the deep purple showed up a beautiful light blue with gently blended white striped blooms. The deep pink vines now have pastel pink blooms and yesterday were 3 pure white ones. I will attempt to remember to get the camera and upload a picture of this. Here is a picture of the deep purple Grandpa Ott's flower. The flowers now are a gorgeous combination, surely. And I am not complaining, really. It's just that when I was saving seeds, I had purple seeds and I had pink seeds. Now, I do not know what I have and therefore all my Morning Glory seeds are needing to be called mixed colors. I would like to know how a vine that was producing only one color flower for 2 months suddenly begins to bloom a different color. Nothing has changed except the weather. The nights are growing chillier.