Too much carbon?

[Tacklebuster]

I have an 05 150 Yami fourstroker. I always have some black carbon streaks at the end of the day to wipe off at the back of the motor but yesterday I had a thick black streak that was about an inch and a half wide and about a foot long. I have never had that much at the end of a trip. Is that anything to be concerned about? I even had some that was coming out of the little hole that is just above the prop itself