Assuming "cause a brushfire" means intentional causing, rather than unintentional causing during commission of another arson, that's certainly an alarming trend. I live in a region of Canada that's had seasonal forest fires for as long as I remember and I don't recall any of them being intentionally set. Not good to see this emerge as a crime trend although I'm, in a way, not surprised given I've wondered for awhile why terrorists haven't been using forest fires as a tactic given the potentially low risk to mayhem ratio.