You take good care of your sled and want things nice. Though, IMO I would leave it. That spot isn't that bad considering. It's not bad enough to knick the seal. Just polish it a little with very fine emery cloth if your worried.
Last year I got a leftover 2016. You could tell it was put away wet after being next to the road a few times. Lots of oxide on much of the aluminum and the shock shafts were pitted bad. Especially where the rubber bumpers sat on the shaft.
The center shock shaft looked perfect and like it was made from much better metal, because it is.
They sent me new shafts after polaris authorized it. To tell you the truth, the new shafts didn't look great either. They weren't pitted, but you could see how they could easily do so. They are made from some funky looking metal. I looked at them under a microscope at work. Polaris defiantly cut cost to the bone on these. Likely to afford the machining for the needle.
If I had these shafts machined for free at a local trade school I would still complain about the quality. They just look junky.
Your fighting an uphill battle with these shafts because if the junky metal they're made of. Keep them juicy with some good anti corrosion spray or minimally wd40 whenever you store the sled for more than a week. Especially when it gets warm in the presence of any road salt.