It is possible, and has contributed to other apparatus fires in the past. Consider that an air filter is nothing more than paper and is in an environment where there is plenty of oxygen moving rapidly through it. NFPA 1901 actually has a requirement for ember separators in apparatus, but I'm not sure what year that was put in or on what apparatus they are required in.
I feel dumb, yo would thinkbeing in the auto industry I would know that..lol Around here we have to mostly park the truck and run hose or hike to a brush fire, not alot of flat lands here.