Actually, it was about 4 rolls that this happened to, in varying amounts. The other 5 rolls that went through the same camera on the same trip were perfectly fine. I didn't develop them - they were done by a local Ritz last fall. It only occurs near the start of the roll and tapers off along it. On 2 rolls, it tapers off quickly and only ruined one frame. On this roll, it takes awhile and is still visible at the sprocket holes a few frames along. It sorta looks like the film could have been rolled up and exposed while rolled, but I'm not positive about this. All of the film was exposed to one X-ray zap as this was on my Costa Rica trip. Again, only 4 of the rolls were affected - all were together in the same bag (though probably aligned differently).