Classic cinch marks.
Cinch marks are caused by film rubbing against itself. For instance, if you took a piece of rolled up film and pulled on the tail to tighten the roll.
It could have happened while you were rerolling the film.
It is possible that it happened during processing.
It is also possible that it happened inside the camera: If the amount of drag on the payout side is too high, each time the film advances a little series of cinch marks will form.