All my unused film was in my checked bag. All my used film went through the carry on scanner and developed fine.
My ASA 400 Arista EDU film went through an TSA's xray machine it it was fine. I lost my Leatherman though. They saw it on the Xray machine and took it. Oh well....
Another friend (now former friend) was escorted by TSA to the street for having some darts in his carry-on bag. I suspect he said something like, "I'll not give up my darts unless you prythem out of my cold, dead hands".
It looks like X-ray damage to me.
I'm guessing it WAS x-ray damage - though I have never seen the like. Good rule - NEVER put film in checked baggage! In the last 10 years I have traveled with ISO 100 film to China 3 times, Europe 4 times and other domestic travels. I always let my film be scanned by carry-on TSA or Chinese or Germans and have not suffered a trace of scan damage. In Italy 10 years ago I made two exposures on 4x5 Tmax 100 film pack and put one in checked baggage and the other in for-scan carry on. The film in the checked bag DID show a Zone I fog streak but it could have been printed through. Develope the rest of your film - you have nothing to lose and maybe something to gain!