Strings break. It is a fact of life for harpists.
Sometimes you see it coming, but most of the time strings break without warning, and gut strings break more often than nylon, synthetic, and wire strings. If you play the harp for any length of time, you come to accept and expect a certain level of breakage and unpredictability from your gut strings.
But in the last several years, many harpists who use Bow Brand strings have noticed an alarming increase in the frequency of broken gut strings and a change in how they are breaking.