Was it Kodak IR film that you had xrayed? If it even comes out of the plastic film canister it will get fogged. I've already had it happen to me when I forgot to unload my rewound film from my camera to the plastic canister. I had a consistent light leak from my light trap that went through every single layer. I was thinking of putting my still sealed boxes in the lead xray bags and keep in my carry on.
I will try several options and just take lots of photographs.