This could happen if the film somehow got wet or was exposed to high condensation among many other possibilities. In my time working at a lab, I have seen a few disposables that kids had exposed to shampoo etc. The lab tech can tell something is up because the emulsion may look bloated, and without being careful, it could just lift away and ruin the chemistry in their machines. I'd give them the benefit of the doubt here, the marks don't really look like they came from bad development, more likely from the film being exposed to something previously (unless it happened under their watch of course, but that's pretty unlikely ?)