Tiny Tuesday: "Shattered star"

This morning, we noticed this little crack in one of the panes of the kitchen window. It's a bit of a mystery. Bird feeders occasionally get knocked against the window but this is much lower than them, and the squirrels do sometimes get a bit over-enthusiastic in their nut raiding and fall against the glass but again it's an odd location for that. Now and then in the course of opening/closing the roller blind it "escapes" and the the toggle bit on the end of the string hits the glass, but neither of us can remember that happening recently. And there are no projectiles on the ground, and on close inspection, there is no chip out of the glass at the centre of the star either inside or outside. Bizarre!