Back From Machine Shop Not Good!

ok so few weeks ago i got my 350 back from machine shop it had bottem end assy bearings/crank/rods/pistons/ bored .030 & deck shaved. so i got it back in my shop and covered/ wrapped in plastic until i got my other parts.

Yesterday I put the oil pump/tray/pan/cam/timing gear/chain/cover/ balancer i then oiled the cyls as i was putting flywheel on and when turning it over i noticed on #3 a vertical mark on the outer wall so immediately looked at it grabbed my new lint free rag wiped cyc clean and my finger nail can catch it can even feel with finger.
I then looked at all other cylinders and noticed they all have a similar line in that spot??? but none of the others i can feel with my fingernail. Heres some pics.
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