Minecraft PE world randomly on fire?

I haven't played in almost 5 days because I had eye surgery. Anyway when I logged in to play some of my world was randomly on fire. T was easy to fix with the new update, I just switched to creative mode, out it out and switched back. Was it just a glitch, or could it have been something elts.

If you were near a lava pool, it may have spread some fire around. But other than that, a person must have done it. If you have siblings or friends with access to your phone, you may wanna question them, haha. Sorry I don't know what else could have done it. Hope I helped

Lava Pools can start fires Or it could of been a Griefer could of also been a Troll.