Looks exactly like the casting flaws I had on my Kingquad clutch. I was parting it out so I took a dremel tool and ground one down a bit. It disappeared without going deep at all into the surface. Any cast parts can have those marks.
If you are too concerned with it, I can sell you a stock primary if the price is right since I replaced mine with the VFJ. Really, I'm kidding though. It's normal. Run it, or replace it with a better primary if you want to see what a Can Am can really do!