Thought I'd share this: The small bolts that attach the roof rack/bars had rusted and broken on my 2014 wagon (estate). I only noticed when I heard some rattling and when I checked, one of the bolts had sheared off completely. When removing the bolt from the other side, that broke too, both bolts had corroded down to the diameter of a matchstick. I replaced them with 10mm headed stainless bolts from my local hardware shop.
The car lives outside and the roof racks have been on for 9 years but it might be worth a quick check. Strangely it was only the rear bolts that had failed, the front ones were still fine as were the larger bolts that bolt into the roof rails.