It wouldn't be the first fire that a RR started recently. I believe both the UP and BNSF have been fined in the past 4-5 years for starting fires along the ROW just here in the PNW.
Sometimes they run water cars in fire prone areas to prevent it.
Lots of deferred maintenance going on in the railroad industry in the last decade so I can totally see a few sparks from a locomotive with a bad turbo or bad brake shoes causing something to ignite.