Small chips close the edge of a windshield are much more likely to spread right away because of the top tension

https://zoom-wiki.win/index.php/Auto_Glass_Replacement_Myths_Debunked:_What%E2%80%99s_True_and_What%E2%80%99s_Not%3F

Small chips close to the brink of a windshield are more likely to spread shortly thanks to increased rigidity, requiring quick cognizance.