theReynoldI own 3 Massdrop brass AAA flashlights but I have never seen something like this. I would ask Massdrop because that is not normal, these lights are made from solid Brass.
TeletinIt seems like tarnish, I used some metal polish on it and seems better. Looks like some kind of clear coat or lacquer was missing? Have bought other high quality brass items and they didn't tarnish as quickly as this.
theReynoldIt is rusted...not even patina any more....this flash light has no finish on it due to the purpose to patina nicely. you need to look after it if you live in a wet environment.