Being a careful driver, with lots of experience abroad, I don't usually take the additional insurance, and am now fighting a bill for Euro's: 361 for a tiny stone chip!
Our vehicle, while a virtually new/convertible, had hundreds of small chips, dents and dinks all over it, so was signed off with 'x's everywhere, but guess what, no 'x' for the windscreen. My fault, I didn't examine it, thinking I had everything covered. When we returned it, they immediately focused on the windscreen, and identified this tiny chip.
This appears to be a regular [problem]...so watch out!
This occurred with 'Guerin' at Faro airport.