NS 5294 sparking?

I was walking the dogs down Bank St. in Wyckoff the other night (because it parallels the tracks) and I caught NS 5294 going by with a short string of covered hoppers. The only reason this is notable is that sparks or embers were coming out of the exhaust stack as it went by. Is that common? I have never seen it before - not even from 5294, which probably goes by my house just about every day. It wasn't like fireworks or anything, but a couple/few at a time, consistently, as it went by. That seems like it's maybe not a good thing.

I would guess that it's carbon burning off..........nothing unusual if that's the case.

Charlie

Excessive idling followed by heavy loads can result in sparks. More typical in a roots blown engine than in a turbo charged engine.
Brian