about 2 days ago when i was shooting i felt the top 6-8 inches fell dirty and not smooth. when i examined the shaft i noticed 2 1-inch long black lines and about a dozen very small black lines no bigger than 1/8 of an inch. i bought it off a friend about 2 weeks ago and it is a year old but when i bought it the shaft was smooth almost like new. anybody know what the problem?