I think the film was rubbing against something in the camera.

If it's done this on multiple rolls of film in factory cartridges, it likely isn't because of some crud in the cartridge opening.
Since it is from factory cartridges, there's no possibility of a problem with a bulk film loader. (These are factory cartridges? Right?)

I doubt that it occurred in processing:
A) You said it was dip-and-dunk.
B) If it occurred in a processing machine, the marks would probably be straighter.

Maybe it occurred during packaging like Hairydale said. Good possibility.

I would still check your camera. Look at the pressure plate, especially, but follow the film path from start to finish and clean/check everything along the way. There could be some crud built up inside, somewhere.

If nothing else, this will serve to eliminate a problem with your camera when you go back to your lab guys to complain.