That does not look like any light leak I've seen. I'm guessing X-Ray damage by the newer airport machines. I used to think that X-Ray damage showed up as wavy lines of increased exposure, but not so with the new scanners, apparently. See the
Kodak page for examples. An excerpt from that page:
"Fog caused by the new baggage scanners is usually more pronounced than fog caused by other means. Fog from the CAT scan type of scanner typically appears as soft-edged bands 1/4 to 3/8 inch (1 to 1.5 cm) wide. The orientation of the fog stripe depends on the orientation of the film relative to the X-ray beam. The banding may be linear or wavy and can run lengthwise or horizontally on the film. It can also undulate, depending on the combination of the angle of exposure and the multiple laps of film on the roll."