Merry Christmas Bokeh

I have NO idea why this turned out like it did. I took a picture of our Christmas lights while inside, looking through the window of our front door. Our door has a fan shaped window on the upper part with sections of beveled glass. I purposely wanted the Christmas lights thrown out of focus but I can't explain why it looks like a grid or checkerboard looking pattern. Weird, huh? I put my camera on manual focus because I wanted the lights to be as out of focus as possible. I'm pretty good at manual focus when I don't really need to focus on anything- just make it out of focus. Hee-hee!  Now I put the auto focus back on and focused on the lights. Exciting. Huh. And not that this is much better, but it's the same string of lights on manual focus, out of focus. More of the same pattern: lights in focus, lights out of focus. Exciting, huh?