Piston

I have a 2013 Pro 800 with I think around 780 miles on it all mountain riding in Wyoming. I had my pipe and exhaust valves out to clean them and was looking at the pistons. I noticed a strange mark on the Pto side piston. Not a score mark or anything because it is parallel to the top of the piston not perpendicular to the piston. It is about 3/8" long. I can't tell for sure if it is a crack or not. I'm not sure if it is the piston skirt starting to crack or not. Here are a couple pictures of the pto piston. Any recommendations? I haven't talked to my dealer yet; just noticed it this afternoon. I have the 4 year warranty. My main concern is just not to have a failure during the season.

I took the y pipe off and then I could reach the piston. I can't really feel a lip at all or catch the mark with my fingernail. And I suppose that if it was a piston skirt cracking it probably wouldn't start in the middle.

Is there any reason that I shouldn't reuse the Y pipe gasket? It didn't rip at all taking it off and looks good yet.